Dtv transmitting system and method of processing data in dtv transmitting system

ABSTRACT

A DTV transmitting system includes two pre-processors. The first pre-processor codes high-priority enhanced data for forward error correction (FEC) and expands the FEC-coded data. The second pre-processor codes low-priority enhanced data for FEC and expands the FEC-coded low-priority enhanced data. The DTV transmitting system further includes a data formatter generating enhanced data packets including the pre-processed data, a multiplexer multiplexing the enhanced data packets with main data packets, an RS encoder RS-coding the multiplexed data packets, a data interleaver interleaving the RS-coded data packets, and a block processor which codes each block of enhanced data in the interleaved enhanced data packets and bypasses the interleaved main data packets.

This application claims the benefit of the Korean Patent Application No.10-2006-0019650, filed on Feb. 28, 2006, which is hereby incorporated byreference as if fully set forth herein. Also, this application claimsthe benefit of the Korean Patent Application No. 10-2006-0089736, filedon Sep. 15, 2006, which is hereby incorporated by reference as if fullyset forth herein. This application also claims the benefit of U.S.Provisional Application No. 60/821,245, filed on Aug. 2, 2006, which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital communication system, andmore particularly, to a DTV transmitting system and a method ofprocessing data in the DTV transmitting system. Although the presentinvention is suitable for a wide scope of applications, it isparticularly suitable for transmitting and receiving digital broadcastsignal.

2. Discussion of the Related Art

Presently, the technology for processing digital signals is beingdeveloped at a vast rate, and, as a larger number of the population usesthe Internet, digital electric appliances, computers, and the Internetare being integrated. Therefore, in order to meet with the variousrequirements of the users, a system that can transmit diversesupplemental information in addition to video/audio data through adigital television channel needs to be developed.

Some users may assume that supplemental data broadcasting would beapplied by using a PC card or a portable device having a simple in-doorantenna attached thereto. However, when used indoors, the intensity ofthe signals may decrease due to a blockage caused by the walls ordisturbance caused by approaching or proximate mobile objects.Accordingly, the quality of the received digital signals may bedeteriorated due to a ghost effect and noise caused by reflected waves.However, unlike the general video/audio data, when transmitting thesupplemental data, the data that is to be transmitted should have a lowerror ratio. More specifically, in case of the video/audio data, errorsthat are not perceived or acknowledged through the eyes or ears of theuser can be ignored, since they do not cause any or much trouble.Conversely, in case of the supplemental data (e.g., program executionfile, stock information, etc.), an error even in a single bit may causea serious problem. Therefore, a system highly resistant to ghost effectsand noise is required to be developed.

The supplemental data are generally transmitted by a time-divisionmethod through the same channel as the video/audio data. However, withthe advent of digital broadcasting, digital television receiving systemsthat receive only video/audio data are already supplied to the market.Therefore, the supplemental data that are transmitted through the samechannel as the video/audio data should not influence the conventionalreceiving systems that are provided in the market. In other words, thismay be defined as the compatibility of broadcast system, and thesupplemental data broadcast system should be compatible with thebroadcast system. Herein, the supplemental data may also be referred toas enhanced data. Furthermore, in a poor channel environment, thereceiving performance of the conventional receiving system may bedeteriorated. More specifically, resistance to changes in channels andnoise is more highly required when using portable and/or mobilereceiving systems.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a DTV transmittingsystem and a method of processing data in the DTV transmitting systemthat substantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of the present invention is to provide a DTV transmittingsystem and a method of processing data in the DTV transmitting system,which are suitable for transmission of enhanced data and resistantagainst noise

Another object of the present invention is to provide a DTV transmittingsystem and a method of processing data in the DTV transmitting system,which are capable of performing additional encoding and stratifying forenhanced data, according to degree of importance of the enhanced data,and transmitting it thereto, thereby enhancing receiving performance ofa receiving system.

Yet another object of the present invention is to provide a DTVtransmitting system and a method of processing data in the DTVtransmitting system, which are capable of stratifying known data, whichare identified at transmitting/receiving ends, and enhanced data, andmultiplexing them with main data, thereby enhancingtransmitting/receiving performance.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital television (DTV) transmitting system includes first and secondpre-processors. The first pre-processor pre-processes enhanced datahaving a high priority by coding the enhanced data for forward errorcorrection (FEC) at a first coding rate and by expanding the FEC-codedenhanced data at a first expansion rate. Similarly, the secondpre-processor pre-processes enhanced data having a low priority bycoding the enhanced data at a second coding rate and expanding theFEC-coded enhanced data at a second expansion rate. For example, thefirst coding rate may be higher or lower than the second coding rate,and the first expansion rate may be different from the second expansionrate.

The DTV transmitting system further includes a data formatter, amultiplexer, a first RS encoder, a first data interleaver, and a blockinterleaver. The data formatter generates enhanced data packetsincluding the pre-processed high-priority and low-priority enhanceddata. The multiplexer then multiplexes the enhanced data packets withmain data packets. The first RS encoder RS-codes the multiplexed datapackets by adding first systematic parity data to each main data packetand adding non-systematic RS parity place holders to each enhanced datapacket. The first data interleaver interleaves the RS-coded datapackets, and the block processor codes each block of enhanced data inthe interleaved enhanced data packets and bypasses the interleaved maindata packets.

The first data interleaver outputs a group of interleaved data packetshaving a head region, a body region, and a tail region. The body regionmay include a plurality of consecutive enhanced data packets only, andthe plurality of consecutive enhanced data packets may be high-priorityenhanced data packets. On the other hand, low-priority enhanced datapackets may be included in the head or tail region.

The DTV transmitting system may further include a data de-interleaver,an RS parity remover, a second RS encoder, a second data interleaver, abyte-symbol converter, and a trellis encoder. The data de-interleaverde-interleaves the main and enhanced data packets outputted from theblock processor, and the RS parity remover removes the first systematicparity data and the non-systematic RS parity place holders from thede-interleaved main and enhanced data packets, respectively. The secondRS encoder then RS-codes the main and enhanced data packets outputtedfrom the RS parity remover by adding second systematic parity data toeach main data packet and adding non-systematic parity data to eachenhanced data packet. The second interleaver interleaves the main andenhanced data packets outputted from the second RS encoder. Thebyte-symbol converter converts the data packets outputted from thesecond data interleaver into symbols, and the trellis encodertrellis-encodes the converted symbols.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a schematic block diagram of a digital broadcasttransmitting system according to an embodiment of the present invention;

FIG. 2 illustrates a detailed diagram of a Trellis encoding unit of FIG.1 according to an embodiment of the present invention;

FIG. 3 illustrates a representation of data configuration at an inputend of a data interleaver in a digital broadcast transmitting systemaccording to the present invention;

FIG. 4 illustrates a representation of data configuration at an outputend of a data interleaver in a digital broadcast transmitting systemaccording to the present invention;

FIG. 5 illustrates a data group according to the present invention;

FIG. 6 and FIG. 7 illustrate schematic block diagrams of embodiments ofthe pre-processor of FIG. 1;

FIG. 8 and FIG. 9 illustrate schematic block diagrams of embodiments ofthe block processor according to the present invention;

FIG. 10 and FIG. 11 illustrate schematic block diagrams of otherembodiments of the block processor according to the present invention;

FIG. 12 illustrates a schematic block diagram of a demodulating unitincluded a digital broadcast receiving system according to an embodimentof the present invention;

FIG. 13 illustrates a block diagram of a digital broadcast (ortelevision or DTV) transmitting system according to another embodimentof the present invention;

FIG. 14 illustrates a block diagram showing a general structure of ademodulating unit within a digital broadcast (or television or DTV)receiving system according to another embodiment of the presentinvention;

FIG. 15 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anembodiment of the present invention; and

FIG. 16 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

The terminologies disclosed the present application is widely used inthis field of the present invention. However, some of them are definedby the inventors. In this case, the newly defined terminologies aredescribed in detail in the following description. Therefore, theterminologies in the present invention will be understood on the basisof the disclosure of the present application.

Enhanced data in the present application may be any of applicationprogram execution files, data having information, such as stockinformation, etc., and video/audio data. Known data may be data which ispreviously known in transmitting/receiving ends, based on a protocol.Main data is indicative of data which can be received by theconventional receiving systems, including video/audio data.

The present invention serves to identify enhanced data havinginformation according to predetermined conditions, and to individuallyor integrally perform additional encoding for the identified enhanceddata, respectively. Here, the conditions for identifying the enhanceddata may be determined by many factors. For example, the enhanced datamay be identified by degree of importance thereof.

Also, in order to group a plurality of enhanced data packets, multiplexthe group with main data, and transmit them, the present inventionstratifies the group to form a plurality of regions, and classifiestypes of inserted data, and processing methods, etc., according tocharacteristics of stratified regions.

In addition, the present invention can classify enhanced data into Ntypes of enhanced data, from high priority to low priority. On the otherhand, although the present invention will be described on the basis ofthe high priority enhanced data and the low priority enhanced data forconvenience of description, it will be easily appreciated that such animplementation is just an embodiment, such that there may be manyembodiments modified therefrom. Therefore, the present invention mustnot be limited to such embodiments.

FIG. 1 illustrates a schematic block diagram of a digital broadcasttransmitting system according to an embodiment of the present invention.Namely, the digital broadcast transmitting system inputs the identifiedenhanced data, performs additional encoding for the inputted enhanceddata, individually or integrally, and then multiplexes the encodedresult with main data to transmit it.

The digital broadcast transmitting system includes a pre-processor 101,a packet formatter 102, a packet multiplexer 103, a data randomizer 104,a scheduler 105, a post-processor 110, an RS encoder/non-systematic RSencoder 121, a data interleaver 122, a parity replacer 123, anon-systematic RS encoder 124, a Trellis encoding unit 125, a framemultiplexer 126, and a transmitting unit 130.

The pre-processor 101 inputs enhanced data and then performspre-processing, such as additional block encoding, block interleaving,byte expansion through insertion of null data, etc. Afterwards, thepre-processing result is outputted to the packet formatter 102.

Here, when the inputted enhanced data is the high priority enhanced dataand the low priority enhanced data, the pre-processor 101 performspre-processing, such as additional block encoding, block interleaving,byte expansion, etc., respectively. After that, the data, which isclassified by degree of importance, is outputted to the packet formatter102 while its classified state is kept. The operations of thepre-processor 101 will be described in detail later.

The packet formatter 102 collects the pre-processed enhanced data on thebasis of packet unit, to group them, according to control of thescheduler 105. Here, the packet is indicative of an enhanced data packetof 188 byte unit as MPEG header of 4 bytes is added thereto. Theenhanced data packet can be composed of only enhanced data or only knowndata (or known data places). Also, the enhanced data packet can becomposed of a result in that the enhanced data and the known data aremultiplexed. Later, there may be a detailed description for a rulerelated to formation of data groups in the packet formatter 102.

The packet formatter 102 outputs its output to the packet multiplexer103. The packet multiplexer 103 performs time divisional multiplexingfor the main data packet and the data group, on the basis of TransportStream (TS) packet unit, to output them to the data randomizer 104,according to control of the scheduler 105.

Here, the scheduler 105 generates and outputs a control signal such thatthe packet formatter 102 can multiplex the enhanced data and the knowndata (or known data place holder). Also, the scheduler 105 generates andoutputs a control signal such that the packet multiplexer 103 canmultiplex the main data packet and the data group on the basis of packetunit.

The data randomizer 104 deletes MPEG synchronization bytes from the dataand randomizes the remaining 187 bytes using a pseudo random bytegenerated therein. After that, the randomization result is outputted tothe post-processor 110.

The post-processor 110 includes an RS encoder/non-systematic RS parityplace holder inserter 111, a data interleaver 112, an block processor113, a data deinterleaver 114, and an RS byte remover 115.

The RS encoder/non-systematic RS parity place holder inserter 111performs systematic RS encoding when the randomized data is a main datapacket, and non-systematic RS parity holder insertion when therandomized data is an enhanced data packet. Namely, like theconventional broadcast system, the RS encoder/non-systematic RS parityplace holder inserter 111 performs systematic RS encoding when thepacket of 187 bytes, which is outputted from the data randomizer 104, isa main data packet, and then adds a parity of 20 bytes to the end of the187 byte data, to output it to the data interleaver 112.

On the other hand, the RS encoder/non-systematic RS parity place holderinserter 111 inserts an RS parity place holder, which is composed ofnull data of 20 bytes, into a packet to perform non-systematic RSencoding, when the packet of 187 bytes, which is outputted from the datarandomizer 104, is an enhanced data packet. Also, the RSencoder/non-systematic RS parity place holder inserter 111 inserts thebytes of the enhanced data packet in the places of the remaining 187bytes to output them to the data interleaver 112.

The data interleaver 112 performs data interleaving for the output ofthe RS encoder/non-systematic RS parity place holder inserter 111 andthen outputs the data interleaving result to the block processor 113.

The block processor 113 performs additional encoding for only theenhanced data, which is outputted from the data interleaver 112, andthen outputs it to the data interleaver 114. The data deinterleaver 114performs data deinterleaving for the inputted data and then outputs itto the RS byte remover 115. Here, the data deinterleaver 114 performs areverse operation of the data interleaver 112. The additional encodingprocess of the block processor 113 will be described in detail later.

The RS byte remover 115 deletes the parity of 20 bytes, which is addedin the RS encoder/non-systematic RS parity place holder inserter 111.Here, when the inputted data is a main data packet, last 20 bytes of the207 bytes are deleted, and when the inputted data is an enhanced datapacket, the parity place holders of 20 bytes of 207 bytes are deleted,in which the parity place holders of 20 bytes are inputted to performnon-systematic RS encoding. Such processes are performed to re-calculatea parity since the original data is changed by the block processor 113in the case that the inputted data is enhanced data.

The RS byte remover 115 outputs its output to the RSencoder/non-systematic RS encoder 121.

The RS encoder/non-systematic RS encoder 121 adds a parity of 20 bytesin the packet of 187 bytes, which is outputted from the RS byte remover115, and then outputs it to the data interleaver 122. Here, like theconventional broadcast system, the RS encoder/non-systematic RS encoder121 performs systematic RS encoding to add a parity of 20 bytes to theend of the data of 187 bytes, when the inputted data is a main datapacket. When the inputted data is an enhanced data packet, the RSencoder/non-systematic RS encoder 121 determines 20 places for paritybyte in the packet and then inserts the RS parity of 20 bytes in thedetermined parity byte place, in which the RS parity of 20 bytes isobtained through non-systematic RS encoding.

The data interleaver 122 is implemented with a convolution interleaverof byte unit, and is operated by the interleaving rule like the datainterleaver 112.

The data interleaver 122 outputs its output to the parity replacer 123and the non-systematic RS encoder 124.

It is necessary to initialize a memory of a Trellis encoding unit 125such that the output data of the Trellis encoding unit 125, which islocated the rear end of the parity replacer 123, is used as known datadefined in transmitting/receiving ends. Here, in order to initialize thememory of the Trellis encoding unit 125, it is necessary to generateinitialization data according to the memory state and replace the inputof the Trellis encoding unit with the initialization data. After that,the RS parity affected by the initialization data is re-calculated andneeds to be replaced with the RS parity outputted from the datainterleaver 122.

Therefore, the non-systematic RS encoder 124 inputs a non-systematic RSparity from the data interleaver 122, and initialization data from theTrellis encoding unit 125, and calculates a non-systematic RS parity tooutput it to the parity replacer 123. Here, the non-systematic RS parityis previously calculated for an enhanced packet in which data to bereplaced with the initialization data.

When inputting an enhanced data packet which does not includes a maindata packet or initialization byte to be replaced, the parity replacer123 selects a RS parity and data outputted from the data interleaver 122and outputs them to the Trellis encoding unit 125. On the other hand,when inputting an enhanced data packet including parity byte to bereplaced, the parity replacer 123 selects data outputted from the datainterleaver 122 and RS parity outputted from the non-systematic RSencoder 124, and then outputs them to the Trellis encoding unit 125.

The Trellis encoding unit 125 converts data of byte unit to data ofsymbol unit and performs 12-way interleaving therefor. Afterwards, theinterleaving result is processed by Trellis encoding and then outputtedto the frame multiplexer 126. The detailed configuration of the Trellisencoding unit 125 will be described later.

The frame multiplexer 126 inserts a field synchronization and a segmentsynchronization in the output of the Trellis encoding unit 125 and thenoutputs it to the transmitting unit 130. The transmitting unit 130includes a pilot inserter 131, a modulator 132, and an RF converter 133.Since the operations of the transmitting unit 130 are the same as thatof the conventional ones, a description therefor will be omitted in thisdisclosure.

Trellis Initialization

FIG. 2 illustrates a detailed diagram of a Trellis encoding unit of FIG.1 according to an embodiment of the present invention.

The Trellis encoding unit 125, which can be initialized, includes abyte-symbol converter 201, a multiplexer 202, a Trellis encoder 203 forinputting inputs which are selected as the Trellis encoder 203 operates,and a symbol-byte converter 204 for converting symbol data to data ofbyte unit and outputting it to the non-systematic RS encoder 124, inwhich the symbol data is used to initialize the Trellis encoder 203.

The byte-symbol converter 201 inputs the output data of the parityreplacer 123, on the basis of byte unit, and converts it to symbol unit.After that, the converting result is interleaved and then outputted tothe multiplexer 202.

Generally, the output of the byte-symbol converter 201 is selected bythe multiplexer 202 and then outputted to the Trellis encoder 203.However, when the interleaved data is known data, and the known data isthe beginning of the successively inputted known data sequence, theTrellis encoder 203 must be initialized. Because the Trellis encoder 203has a memory and thus its present output is affected by the presentinput as well as the past input. Therefore, in order to output apredetermined signal at a certain time, the memory of the Trellisencoder 203 must be initialized at a certain value.

When the memory of the Trellis encoder 203 requires initializationthereof, a part of the known data is substituted with an initializationdata to be outputted to the Trellis encoder 203. Afterwards, the memoryof the Trellis encoder 203 is initialized to a predetermined value basedon the initialization data. Therefore, from the time point of theinitialization, the output of the Trellis encoder 203 can be the knowndata which is encoded to comply with the transmitting/receiving ends.

The Trellis encoder 203 can generate an input symbol value forinitialization according to its own memory value. Afterwards, thegenerated symbol value is outputted to the multiplexer 202 and thesymbol-byte converter 204.

The multiplexer 202 selects an initialization symbol instead of theinputted symbol to the Trellis encoder 203, when the inputted data,which is interleaved and converted to a symbol, is known data sequence.Here, the initialization symbol is outputted from the Trellis encoder203. For the other cases, the multiplexer 202 selects the symbolsoutputted from the byte-symbol converter 201 and then outputs them tothe Trellis encoder 203.

The symbol-byte converter 204 inputs initialization symbols outputtedfrom the Trellis encoder 203 and then performs 12-way deinterleavingtherefor to convert them to symbol byte unit. After that, the convertingresult is outputted to the non-systematic RS 124 to re-calculate an RSparity.

Pre-Process

FIG. 3 and FIG. 4 illustrate representations of data configuration atinput and output ends of data interleavers 112 and 122, respectively, ina digital broadcast transmitting system according to the presentinvention. More specifically, as shown in FIG. 3, the data interleaverinputs data, based on packet sequence, from top to bottom and from leftto right. Also, as shown in FIG. 4, the data interleaver outputs datafrom top to bottom and from left to right. Namely, as shown in FIG. 3,the data interleaver outputs A first, and then combination of B and C,combination of D and E, and F last, thereby outputting data as shown inFIG. 4.

Afterward, when a plurality of enhanced data packets are grouped to betransmitted, 104 packets of A, B, C, and D are formed as a single datagroup and then transmitted, as shown in FIG. 3. In this case, whenanalyzing configuration of the output data of the data interleaver ofFIG. 4, the enhanced data in the regions B and C can be continuously andsuccessively outputted but the enhanced data in the region A or D can beoutputted, and combined with main data.

In the present invention, the data group is stratified into three parts,Head, Body and Tail. Namely, on the basis of output of the datainterleaver, the Head is firstly outputted from the data group, the Bodyis outputted after the Head, and the Tail is outputted last. Here, onthe basis of the time after performing data interleaving, the Body isallocated to include a part of or all of the regions where the enhanceddata in the data group are continuously and successively outputted.Here, the Body may include a region where enhanced data isnon-continuously outputted.

FIG. 5 illustrates a data group according to the present invention, inwhich a predetermined number of enhanced data packets form a group, suchthat the group can be divided into Head, Body, and Tail regions.

Left figure of FIG. 5 shows data configuration before performing datainterleaving, and right figure of FIG. 5 shows data configuration afterperforming data interleaving.

FIG. 5 illustrates a diagram for describing a case where 104 packetsform a data group. Since the data interleaver is periodically operatedon the basis of 52 packet units, the data group can be formed on thebasis of 52 packet times.

Also, as shown in FIG. FIG. 5, the Body region for configuration ofdata, which is outputted from the output end of the data interleaver,forms a rectangular shape. Namely, the Body region is set in the datagroup, such that it cannot be mixed in the main data region while it isprocessed, but it can be formed by only enhanced data.

The data group is divided into three regions to be used for differentpurposes. Namely, since the regions corresponding to the Bodies of FIG.5 are configured by only enhanced data without interference of main datawhile they are processed, they have relatively high receivingperformance. On the other hand, since the enhanced data in the Head andTail regions may be mixed with main data while the outputs are outputtedfrom the data interleaver, the receiving performance of the Head andTail regions is relatively lower than that of the Body region.

In addition, in a system in which known data is inserted in the enhanceddata and then transmitted, when successive long segments of known dataare periodically inserted to the enhanced data, the enhanced data can beinserted to a region in which main data is not mixed therewith, on thebasis of the output sequence of the data interleaver. Namely, as shownin FIG. 5, known data with a predetermined length can be periodicallyinserted to the Body regions. However, it is difficult to periodicallyinsert the known data to the Head and Tail regions, and also, it isimpossible to continuously insert a relatively long segment of knowndata thereto. Here, the initialization data for initializing the memoryof the Trellis encoder 203 is allocated to the beginning portion of theknown data sequence.

Also, when a data group is divided into Head, Body and Tail regions, therespective regions can take charge of different services. For example,when enhanced data is divided into high priority enhanced data and lowpriority enhanced data, the high and low priority enhanced data can beallocated to proper regions of the Head, Body and Tail regions in thedata group, respectively. Namely, the high priority enhanced data isallocated to the Body region and the low priority enhanced data isallocated to the Head and Tail regions.

Therefore, when the enhanced data is inputted, the pre-processor 101 canperform pre-processes for the inputted enhanced data, such as blockencoding, block interleaving, byte expansion, etc., considering types ofinputted enhanced data and types of data allocated to the respectiveregions in the data group. Also, the pre-processor 101 can performpre-processes for the inputted enhanced data, considering one of typesof inputted enhanced data and types of data allocated to the respectiveregions in the data group.

FIG. 6 and FIG. 7 illustrate schematic block diagrams of embodiments ofthe pre-processor 101 of FIG. 1. More specifically, FIG. 6 shows apre-processor for integratedly performing pre-process regardless oftypes of inputted enhanced data, and FIG. 7 shows an pre-processor forindividually performing pre-processes according to types of inputtedenhanced data.

As shown in FIG. 6, the pre-processor 101 includes a block encoder 501,a block interleaver 502, and a byte expansion unit 503.

The block encoder 501 serves to encode inputted enhanced data on thebasis of block encoding. For example, the block encoder 501 isimplemented with an RS encoder, a convolution encoder, a low densityparity check (LDPC) encoder, etc., which can use block codes. Also, theblock encoder may selectively adopt a block interleaver 502 according toimplementation objectives.

Application of the block interleaving is related to entire systemperformance. For example, random interleaving, etc., can be usedtherein.

Here, so that the block encoder 501 performs encoding on the basis ofblock unit and the block interleaver 502 performs block interleaving,block size must be determined.

For example, the block size may be set to bit number of enhanced dataincluded in the Body region in the data group, and also the block sizemay be set to bit number of enhanced data included in the Head and Tailregions. Here, the block size for enhanced data in the Body region isapproximately similar to that in the Head and Tail regions. Suchrelation can be shown in FIG. 5. On the other hand, the block sizes arejust an embodiment of the present invention. For example, when thebeginning and end of a block is determined such that the enhanced datacan have their limited lengths, any size of blocks can be available.Therefore, the present invention will not be limited by suchembodiments.

After encoding on the basis of a block coding fashion, the blockinterleaved data undergoes byte expansion through insertion of null bitsin the byte expansion unit 503. Here, the byte expansion unit 503, whichis implemented as an embodiment of the present invention, can extend onebyte to two bytes, four bytes, or any bytes, as null bits are repeatedlyinserted to the data.

As shown in FIG. 7, the pre-processor 101 includes a certain number ofblock encoders, a certain number of block interleavers and a certainnumber of byte expansion units, based on the number N of types ofenhanced data, such that the respective elements can performpre-processes. Here, according to types of enhanced data, the blockencoders, block interleavers and byte expansion units perform differentblock encodings, block interleavings, and byte expansions.

When the enhanced data is classified into high priority enhanced dataand low priority enhanced data, the pre-processor 101 includes at leasttwo encoders each of which is formed by a block encoder, a blockinterleaver and a byte expansion unit.

As shown in FIG. 7, a first encoder denoted by reference numeral 510encodes high priority enhanced data to perform byte expansion therefor,and a second encoder denoted by reference numeral 5N0 encodes lowpriority enhanced data to perform byte expansion therefor. Also, thehigh priority enhanced data is allocated to the Body region in the datagroup in the packet formatter 102 and the low priority enhanced data isallocated to the Head and Tail regions.

In this case, the encoding rate of the block encoder 511 in the firstencoder 510 is set higher than that of the block encoder 5N1 in thesecond encoder 5N0, such that the data transmission rate can beincreased. Because relatively high receiving performance is expected inthe Body region and relatively low receiving performance is expected inthe Head and Tail regions.

On the other hand, since the Body region allocates data having highdegree of importance thereto, when the encoding rate of the blockencoder 511 in the first encoder 510 is set lower than that of the blockencoder 5N1 in the second encoder 5N0, data transmission rate is reducedand error correction is increased.

The encoder according to an embodiment of the present invention isconfigured such that the block encoder 511 of the first encoder 510 isimplemented with a 9/10 LDPC having encoding rate of 9/10, etc., and theblock encoder 5N1 of the second encoder 5N0 is implemented with a ½ LPDCencoder, ½ convolution encoder, etc., each of which has encoding rate of½. On the contrary, another embodiment modified from the aboveembodiment can be configured such that the block encoder 511 of thefirst encoder 510 is implemented with a ½ LPDC encoder, ½ convolutionencoder, etc., each of which has encoding rate of ½ and the blockencoder 5N1 of the second encoder 5N0 is implemented with a 9/10 LDPChaving encoding rate of 9/10, etc. Here, such embodiments are justexemplary examples of the present invention. Namely, since each blockencoder can be implemented with encoders having different encodingrates, the present invention will not limited by such embodiments.

After each encoder performs block coding and block interleavingaccording to types of enhanced data, each byte expansion unit performsbyte expansion. In this case, the number of extended bytes can beidentically or differently set, according to types of inputted enhanceddata and types of data allocated to each region in the data group. Forexample, the high priority enhanced data may be extended by four bytes,and the low priority enhanced data may be extended by two bytes. Also,the enhanced data may be extended by the opposite rates, respectively,or by the same rate. Here, since such expansions can be selectivelydesigned by the inventors, it will be easily appreciated that theycannot limit the scope of the present invention.

The enhanced data, which has undergone byte expansion in each byteexpansion unit, is inputted to the packet formatter 102. Namely, theenhanced data is processed differently by pre-processing according totypes of enhanced data, and then inputted to the packet formatter 102.

The packet formatter 102 allocates the inputted enhanced data to properregions of the Head, Body, and Tail regions in the data group. Forexample, the high priority enhanced data can be allocated in the Bodyregion, and the low priority enhanced data can be allocated to the Headand Tail regions.

Namely, the packet formatter 102 forms data groups, according to typesof the enhanced data, such that the enhanced data can be located in apredetermined place in the Head, Body, and Tail regions after datainterleaving. Also, after predefined known data (or known data placeholder) is inserted to a particular place in the data group according toa particular rule, the result is outputted to the packet multiplexer 103on the basis of MPEG packet unit of 188 byte unit.

Block Process

On the other hand, the block processor 113 performs additional encodingfor only enhanced data to output it. Namely, the block processor 113outputs its inputs without change, when the output of the datainterleaver 112 is main data and in case of MPEG header byte, which isadded in the packet formatter 102, or an RS parity or an RS parity placeholder byte, which is added to the enhanced data packet in the RSencoder/non-systematic RS parity place holder inserter.

Also, similar to the main data, the known data can be outputtedtherefrom without additional encoding, but its processing method may bedifferent from that of the known data.

For example, the packet formatter 102 inserts a known data place holderthereto, and the block processor 113 outputs known data instead of theknown data place holder, in which the known data is generated in theknown data generators 635 and 737 in the block processor. Also, thepacket formatter 102 inserts known data thereto and then block processor113 outputs its input without change.

The former method is illustrated in FIG. 8 and FIG. 10, and the lattermethod is illustrated in FIG. 9 and FIG. 11.

Firstly, as shown in FIG. 8, the block processor 113 includes ademultiplexer 610, a buffer 620, an enhanced encoder 630, and amultiplexer 640.

The enhanced encoder 630 includes a byte-symbol converter 631, a symbolencoder 632, a symbol interleaver 633, and a symbol-byte converter 634.

As shown in FIG. 8, the demultiplexer 610 outputs its output to thebuffer 620 when the inputted data is main data, and to the enhancedencoder 630 when the inputted data is enhanced data.

The buffer 620 delays main data for a certain time, and then outputs itto the multiplexer 640. Namely, when main data is inputted to thedemultiplexer 610, the buffer 620 is used to compensate time delay whichis generated while the enhanced data is additionally encoded.Afterwards, the main data, whose time delay is controlled by the buffer620, is transmitted to the data deinterleaver 114 through themultiplexer 640.

When the known data is inputted, the known data place holder is insertedthereto in the packet formatter 102. The multiplexer 640 of the enhancedencoder 113 selects the training sequence T, which is outputted from theknown data generator 635, instead of the known data place holder andthen outputs it thereto. Therefore, the known data can be outputtedwithout additional encoding.

On the other hand, the byte-symbol converter 631 of the enhanced encoder630 converts the enhanced data byte to four symbols and then outputsthem to the symbol encoder 632. The symbol encoder 632 encodes M bits ofthe enhanced data to N bits to output them. For example, when 1 bit ofthe enhanced data is encoded to 2 bits to output it, M is 1 and N is 2.

For example, assuming that one byte of the enhanced data is extended totwo bytes as null bits are inserted among bits thereof in thepre-processor 101. The byte-symbol converter 631 removes the null bitsof inputted bytes and composes symbols using only effective data bits tooutput them to the symbol encoder 632.

For example, the symbol encoder 632 encodes a symbol having effectivedata of one bit to a symbol of two bits and then outputs it. Also, thesymbol interleaver 633 inputs the output of the symbol encoder 632 toperform block interleaving on the basis of symbol unit.

The block interleaving is related to the total system performance andmay be used in any interleavings, such as a random interleaving.

The block size must be firstly determined, so that the symbol encoder632 can perform encoding on the basis of block unit, and the symbolinterleaver 633 can perform block interleaving. Here, the block size maybe set on the basis of initialization data for a Trellis encoder orregions stratified in the group.

The symbol-byte converter 634 serves to convert output symbols of thesymbol interleaver 633 to bytes and then outputs them to the multiplexer640.

The multiplexer 640 selects main data outputted from the buffer 620,when the inputted data is the main data, and enhanced data, which isencoded in the enhanced encoder 630, when the inputted data is theenhanced data. Also, when the inputted data is a known data placeholder, the multiplexer 640 selects training sequence, which isgenerated in the known data generator 635, to output it to thedeinterleaver 114.

FIG. 8 and FIG. 9 illustrate schematic block diagrams of embodiments ofthe block processor according to the present invention. FIG. 8 and FIG.9 are identical to each other, except for a known data processing part.Namely, FIG. 9 is identical to FIG. 8 except that, when the inputteddata is known data, the demultiplexer 660 outputs the known data to thebuffer 670 such that the buffer 670 can delay a certain time and thenoutput it to the deinterleaver 114 through the multiplexer 680.Therefore, the detailed description for FIG. 9 will be omitted.

Such processes are performed under the assumption that the known data isalready inserted in the enhanced data packet by the packet formatter102.

The symbol encoders 632 and 682 of FIG. 8 and FIG. 9 are implementedwith a ½ encoder, according to an embodiment of the present invention.

The ½ encoder may use any of encoders which encode one bit to two bits,such as a ½ systematic convolution encoder, a ½ non-systematicconvolution encoder, a ½ repeating encoder, a ½ inverting encoder, etc.

The ½ encoder is implemented with a ½ convolution encoder or a ½ lowdensity parity check (LDPC) encoder, etc., which use block codes. Also,the ½ encoder may selectively use symbol interleavers 633 and 683according to implement objectives. The symbol interleavers 633 and 683perform block interleaving on the basis of symbol unit.

Here, since the ½ encoder may be applied to various fields, it will beeasily appreciated that such embodiments will not limit the presentinvention.

FIG. 10 and FIG. 11 illustrate schematic block diagrams of anotherembodiments of the block processor 113 according to the presentinvention.

Firstly, as shown in FIG. 10, the block processor 113 includes ademultiplexer 710, a buffer 720, an enhanced encoder 730 and amultiplexer 740.

The enhanced encoder 730 includes a byte-bit converter 731, an enhancedouter encoder 732, a bit-symbol converter 733, an enhanced inner encoder734, a symbol interleaver 735, and a symbol-byte converter 736.

The enhanced outer encoder 732 serves to encode O bit of the enhanceddata to P bit to output it. For example, when the enhanced outer encoder732 encodes 1 bit of the enhanced data to two bits, the O and P are 1and 2, respectively. Also, the enhanced inner encoder 734 serves toencode Q bit of the inputted data to R bit to output it. For example,when 1 bit of the enhanced data is encoded in two bits in the enhancedinner encoder 734, the Q and R are 1 and 2, respectively.

As shown in FIG. 10, the demultiplexer 710 outputs its input data to thebuffer 720, when the inputted data is main data, and to the enhancedencoder 730 when the inputted data is enhanced data.

The buffer 720 delays main data for a certain time, and then outputs itto the multiplexer 740. Namely, when main data is inputted to thedemultiplexer 710, the buffer 720 is used to compensate time delay whichis generated while the enhanced data is additionally encoded in theenhanced encoder 730. Afterwards, the main data, whose time delay iscontrolled by the buffer 720, is transmitted to the data deinterleaver114 through the multiplexer 740.

When the known data is inputted, the known data place holder is insertedthereto in the packet formatter 102. The multiplexer 740 of the enhancedencoder 113 selects the training sequence T, which is outputted from theknown data generator 737, instead of the known data place holder andthen outputs it thereto. Therefore, the known data can be outputtedwithout additional encoding.

On the other hand, the byte-bit converter 731 of the enhanced encoder730 converts byte of the inputted enhanced data to bit stream. Afterthat, null bits are removed from the extended byte of the bit streamsuch that only effective data can be outputted to the enhanced outerencoder 732. Here, the null bits are inserted to the byte of theenhanced data to generate the extended byte of the enhanced data byte inthe pre-processor 101. The enhanced outer encoder 732 inputs at leastone or more than one effective data hit to encode them, and then outputsone or more than one bit to the bit-symbol converter 733. The bit-symbolconverter 733 converts inputted two bits to one symbol and then outputsit to the enhanced inner encoder 734. Similar to the symbol encoders 632and 682 of FIG. 8 and FIG. 9, the enhanced inner encoder 734 encodes theinputted symbol to output it to the symbol interleaver 735.

The symbol interleaver 735 inputs the output of the enhanced innerencoder 734 to perform block interleaving for it on the basis of symbolunit. The block interleaving is related to the total system performanceand may be used in any interleavings, such as a random interleaving.

Here, the block size must be firstly determined, so that the enhancedinner encoder 734 can perform encoding on the basis of block unit, andthe symbol interleaver 735 can perform block interleaving on the basisof symbol unit. Here, the block size may be set on the basis ofinitialization data for a Trellis encoder or regions stratified in thegroup.

The symbol-byte converter 736 serves to convert output symbols of thesymbol interleaver 735 to bytes and then outputs them to the multiplexer740.

The multiplexer 740 selects main data outputted from the buffer 720,when the inputted data is the main data, and enhanced data, which isencoded in the enhanced encoder 730, when the inputted data is theenhanced data. Also, when the inputted data is a known data placeholder, the multiplexer 740 selects training sequence, which isgenerated in the known data generator 737, to output it to thedeinterleaver 114.

FIG. 10 and FIG. 11 are identical to each other, except for a known dataprocessing part. Namely, FIG. 11 is identical to FIG. 10 except that,when the inputted data is known data, the demultiplexer 760 outputs theknown data to the buffer 770 such that the buffer 770 can delay acertain time and then output it to the deinterleaver 114 through themultiplexer 780. Therefore, the detailed description for FIG. 11 will beomitted.

Such processes are performed under the assumption that the known data isalready inserted in the enhanced data packet by the packet formatter102.

As shown in FIG. 10 and FIG. 11, the enhanced outer encoders 732 and 782and the enhanced inner encoders 734 and 784 are implemented with a ½encoder, according to an embodiment of the present invention.

The ½ encoder may use any of encoders which encode one bit to two bits,such as a ½ systematic convolution encoder, a ½ non-systematicconvolution encoder, a ½ repeating encoder, a ½ inverting encoder, etc.

The ½ encoder is implemented with a ½ convolution encoder or a ½ lowdensity parity check (LDPC) encoder, etc., which use block codes. Also,the ½ encoder may selectively use a symbol interleaver according toimplement objectives. The symbol interleaver performs block interleavingon the basis of symbol unit.

Also, since the ½ encoder may be applied to various fields, it will beeasily appreciated that such embodiments will not limit the presentinvention.

For example, when each of the outer and inner encoders has a ½ encodingrate and the outer encoder is adjacently installed to the inner encoder,the total encoding rate of the enhanced encoder becomes ¼. To this end,the pre-processor 101 performs a byte expansion process in which 3 nullbits are inserted to the data corresponding to one bit.

Also, when byte expansion is performed as the 3 null bits are insertedto the data for one effective bit, only the one effective bit is encodedto two bits in the outer encoder. Here, one of the two bits is locatedat the original effective bit place to be converted to a symbol andanother is located at the second bit place of the null bits so as to beconverted to a symbol. Then, one symbol is re-composed of an effectivebit and a null bit, in which only the effective bit is encoded to twobits in the inner encoder. After that, it is repeatedly performed thatone bit is located at the original effective bit place and another islocated at the null bit place. Therefore, consequently, the system canbe performed at ¼ encoding rate.

On the other hand, since the outer and inner encoding processes are justan embodiment of the present invention, encodings, encoding rates, andencoded data places, etc. can be selectively changed by the encoderdevelopers. Therefore, it will be easily appreciated that theembodiments will not limit the scope of the present invention.

FIG. 12 illustrates a schematic block diagram of a demodulating unitincluded a digital broadcast receiving system according to an embodimentof the present invention. Namely, the demodulating unit performsdemodulating, equalizing for the data transmitted from the digitalbroadcast transmitting system, and then restores the original data.

More specifically, the demodulating unit includes a demodulator 801, anequalizer 802, a known sequence detector 803, a block decoder 804, adata deinterleaver 805, an RS decoder/non-systematic RS parity remover806, and a derandomizer 807.

Also, the demodulating unit includes a main data packet remover 808, apacket deformatter 809, and an enhanced data processor 810.

Namely, the broadcast signal of a specific channel tuned through a tuneroutputs to the demodulator 801 and the known sequence detector 803.

The demodulator 801 performs automatic gain control, carrier recoveryand timing recovery, etc., for the inputted broadcast signal to generatea baseband signal, and then output it to the equalizer 802 and the knownsequence detector 803.

The equalizer 802 compensates distortion in the channel included in thedemodulated signal, and then outputs it to the block decoder 804.

Here, the known sequence detector 803 detects known data place, which isinserted in the transmitting end, from input/output data of thedemodulator 801, and then outputs symbol sequence of the known datatogether with information of the known data place, in which the symbolsequence is generated in the known data place, to the demodulator 801,the equalizer 802, and the block decoder 804. Here, the input/outputdata of the demodulator 801 is indicative of data before or afterperforming demodulation. Also, the known sequence detector 803 outputsinformation to the block decoder 804, such that enhanced data (which hasbeen processed by any one of enhanced encoders of FIG. 8, FIG. 9, FIG.10, and FIG. 11), which performs additional encoding in the transmittingend, can be discriminated from the main data, which does not performadditional encoding, by the block decoder 804 in the receiving end, andsuch that a beginning point of a block of the enhanced encoder can benotified.

The demodulator 801 enhances its demodulation performance using theknown data symbol sequence when performing timing restoration or carrierrestoration. The equalizer 802 enhances its equalization performanceusing the known data. Also, the equalization performance may be enhancedas the decoding result of the block decoder 804 is feedback to theequalizer 802.

On the other hand, the data, which is inputted to the block decoder 804from the equalizer 802, is main data or enhanced data. Here, the maindata undergoes only Trellis encoding but does not undergo additionalencoding in the transmitting end, and the enhanced data undergoesadditional encoding and Trellis encoding.

When the inputted data is enhanced data or known data, the block decoder804 performs Viterbi decoding for the inputted data or hard decision fora soft decision value to output the result. Also, the transmitting endregards RS parity byte and MPEG header byte, which are added to theenhanced data packet at the transmitting end, as main data, and does notperform additional encoding therefor. Therefore, Viterbi decoding isperformed or hard decision is performed for soft decision value, suchthat the result can be outputted.

On the other hand, when the inputted data is enhanced data, the blockdecoder 804 outputs a soft decision value for the inputted enhanceddata. Such a process is performed to enhance performance of additionalerror correction decoding which is performed for the enhanced data inthe enhanced data processor 810.

The enhanced data processor 810 inputs the soft decision value and thenperforms additional error correction decoding therefor. Namely, theenhanced data processor 810 performs error correction decoding for theenhanced data which has undergone soft decision. The error correctiondecoder is implemented with any of an RS decoder, a convolution decoder,a low density parity check code (LDPC) decoder or a turbo decoder, etc.

Namely, when the inputted data is enhanced data, the block decoder 804performs decoding for the block processor 113 and the Trellis encoder203. Here, the block encoder of the pre-processor at the transmittingend is regarded as an outer encoder, and the Trellis encoder 203 of theblock processor 113 is regarded as an inner encoder.

So that the performance of the outer encoder can be maximized when theadjacent encodes are decoded, a decoder for inner encoders must output asoft decision value. Therefore, it is preferable such that the blockdecoder 804 does not output a hard decision value to the enhanced databut a soft decision value.

When the inputted enhanced data is processed by the enhanced encoders ofFIG. 8 and FIG. 9, a soft decision value, which is outputted as softdecision decoding for Trellis encoding is performed, is outputted to asymbol deinterleaver (not shown) which performs an inverse operation ofthe symbol interleaver, to perform deinterleaving therefor. After that,the deinterleaved data is decoded.

Also, when the inputted enhanced data is processed by the enhancedencoders of FIG. 10 and FIG. 11, symbol deinterleaving for a softdecision value for Trellis encoding is performed and then inner decodingis performed, in which the inner decoding is a reverse process of theinner encoder. Similar to Trellis decoding, the inner decoding resultmust be used to obtain a soft decision value using the decoder which iscapable of obtaining the soft decision value. After that, as the softdecision value is re-processed by outer decoding which is a reverseoperation of the inner encoder, the decoded enhanced data can beobtained.

When a Trellis decoder and an encoder for the symbol encoder of FIG. 6(or inner encoder of FIG. 7) compose a soft decision decoder, the softdecision value of the Trellis decoder can assist decision of the encoderfor the symbol encoder of FIG. 6 (or inner encoder of FIG. 7). Thedecoder receiving such assistance of the Trellis decoder can return itssoft decision value to the Trellis decoder, such that it can assistdecision of the Trellis decoder. Such decoding is referred to as turbodecoding. When the turbo decoding is adopted, the total decodingperformance can be enhanced.

There are algorithms to output the soft decision value for the enhanceddata, such as Soft Output Viterbi Algorithm (SOVA), Maximum A Posteriori(MAP), and Suboptimum Soft output Algorithm (SSA) etc. As thetransmitting method of the present invention is described above, when ablock is used for initialization of a memory state of the Trellisencoder such that the Trellis encoder of the Trellis encoding unit isreturned from a predetermined state value to another predetermined statevalue, the soft decision value using algorithms, such as a MAP algorithmor a SOVA, etc., is outputted, thereby obtaining optimal performance.

On the other hand, the block decoder 804 outputs its output to thedeinterleaver 805. The deinterleaver 805 performs deinterleaving andoutputs the deinterleaving result to the RS decoder/non-systematic RSparity remover 806. Here, the deinterleaver 805 performs a reverseoperation of the data interleaver of the transmitting end. The RSdecoder/non-systematic RS parity remover 806 performs systematic RSdecoding when the inputted packet is main data packet and removesnon-systematic RS parity bytes from the packet when the inputted packetis enhanced data packet, to output the result to the derandomizer 807.

The derandomizer 807 inputs the output of the RS decoder/non-systematicRS parity remover 806 to generate pseudo random byte which is identicalto that of the randomizer of the transmitting system and then performs abitwise exclusive OR (XOR) operation. Afterwards, the derandomizer 807inserts MPEG synchronization byte to each packet and then outputs it onthe basis of 188 byte packet. The output of the derandomizer 807 isoutputted to a main MPEG decoder (not shown) and to the main data packetremover 808, simultaneously. The main MPEG decoder decodes only a packetcorresponding main MPEG. Such processes are performed because theenhanced data packet is not used in the conventional receivers or theenhanced data packet has null or reserved PID, and thus because it isnot decoded in the main MPEG decoder and ignored.

However, it is difficult to perform the XOR operation between the softdecision value of the enhanced data and the pseudo random bit.Therefore, as the data outputted to the main MPEG decoder is describedin detail above, the soft decision value is determined by hard decisionon the basis of sign thereof, and then performs the XOR operation withthe pseudo random bit to output the result. Namely, when the signs ofthe soft decision value are positive and negative, the decision valuesare set to 1 and 0, respectively. Therefore, the decision values performthe XOR operation with a pseudo random bit.

On the other hand, as the enhanced data processor 810 is describedabove, since soft decision is required to enhance its performance whenerror correction code is decoded, the derandomizer 807 generates anadditional output for the enhanced data to output it to the main datapacket remover 808. For example, the derandomizer 807 inverts sign ofthe soft decision value, and then outputs it, when the pseudo random bitis 1. Here, the pseudo random bit performs the XOR operation for thesoft decision value of the enhanced data bit is 1. On the other hand,when the pseudo random bit is 1, the derandomizer 807 outputs it withoutchange.

When the pseudo random bit is 1, the change of sign of the soft decisionvalue is because the data bit outputted from the transmitting system isinverted. Namely, 0⊕1=1 and 1⊕1=0.

In other words, in a case that the pseudo random bit, which is generatedin the derandomizer, is 1, when the pseudo random bit performs an XORoperation with the hard decision value of the enhanced data bit, itsvalue is inverted. Therefore, when the soft decision value is outputtedafter its sign is changed to opposite sign.

The main data packet remover 808 takes only the soft decision value ofthe enhanced data packet from the output of the derandomizer 807 andthen outputs it. Namely, the main data packet remover 808 removes maindata packet of 188 byte unit from the output of the derandomizer 807,and then takes only the soft decision value of the enhanced data packetto output it to the packet deformatter 809.

The packet deformatter 809 removes a MPEG header having PID for enhanceddata from the input data thereof to obtain a packet of 184 byte units,in which the MPEG header is inserted thereto in the transmitting systemin order to be identified with a main data packet. After that, the 184byte packets are collected to form a group of a predetermined size, andthe known data, which is inserted thereto in the transmitting system toperform demodulation and equalization, is removed from a predeterminedplace. Afterwards, the Head, Body, Tail regions in the data group areidentified to be outputted to the enhanced data processor 810. Namely,the enhanced data, which is individually processed by pre-process in thepre-processor of the transmitting system, is identified on the basis ofits type and then outputted thereto.

The output of the packet deformatter 809 is inputted to the enhanceddata processor 810.

The enhanced data processor 810 performs block deinterleaving and blockdecoding for the enhanced data which has undergone soft decision.

The enhanced data processor 810 performs a reverse operation of thepre-processor of the transmitting end. The pre-processor of thetransmitting system individually performs block encoding and blockinterleaving for inputted enhanced data according to types of theenhanced data, and byte expansion therefor as null bits are inserted orbits are repeatedly inserted. Then, the enhanced data processor 810performs the reverse operation of the pre-processor of the transmittingend. Namely, the enhanced data processor 810 individually processes theinputted enhanced data according to the types of the enhanced data andthen outputs the enhanced data in a state where the enhanced data isidentified on the basis of degree of importance or priority, as theenhanced data is identified on the basis of degree of importance orpriority at the transmitting end. Namely, the enhanced data processor810 removes the null bits or repeated bits from the inputted enhanceddata that has undergone soft decision, on the basis of the type thereof.Here, the null bits or repeated bits are used for byte expansion in thepre-processor. Afterwards, the enhanced data processor 810 performsblock deinterleaving and block decoding for the removal of the null bitsand repeated bits to output the finally processed enhanced data.

For example, the finally processed enhanced data is divided into highpriority enhanced data and low priority enhanced data to be outputted.

FIG. 13 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to an embodiment of the presentinvention. The digital broadcast (or DTV) transmitting system includes apre-processor 910, a packet multiplexer 921, a data randomizer 922, aReed-Solomon (RS) encoder/non-systematic RS encoder 923, a datainterleaver 924, a parity byte replacer 925, a non-systematic RS encoder926, a frame multiplexer 928, and a transmitting system 930. Thepre-processor 910 includes an enhanced data randomizer 911, a RS frameencoder 912, a block processor 913, a group formatter 914, a datadeinterleaver 915, and a packet formatter 916.

In the present invention having the above-described structure, main dataare inputted to the packet multiplexer 921. Enhanced data are inputtedto the enhanced data randomizer 911 of the pre-processor 910, wherein anadditional coding process is performed so that the present invention canrespond swiftly and appropriately against noise and change in channel.The enhanced data randomizer 911 randomizes the received enhanced dataand outputs the randomized enhanced data to the RS frame encoder 912. Atthis point, by having the enhanced data randomizer 911 perform therandomizing process on the enhanced data, the randomizing process on theenhanced data by the data randomizer 922 in a later process may beomitted. Either the randomizer of the conventional broadcast system maybe used as the randomizer for randomizing the enhanced data, or anyother type of randomizer may be used herein.

The RS frame encoder 912 receives the randomized enhanced data andperforms at least one of an error correction coding process and an errordetection coding process on the received data. Accordingly, by providingrobustness to the enhanced data, the data can scatter group error thatmay occur due to a change in the frequency environment. Thus, the datacan respond appropriately to the frequency environment which is verypoor and liable to change. The RS frame multiplexer 912 also includes aprocess of mixing in row units many sets of enhanced data each having apre-determined size. By performing an error correction coding process onthe inputted enhanced data, the RS frame encoder 912 adds data requiredfor the error correction and, then, performs an error detection codingprocess, thereby adding data required for the error detection process.The error correction coding uses the RS coding method, and the errordetection coding uses the cyclic redundancy check (CRC) coding method.When performing the RS coding process, parity data required for theerror correction are generated. And, when performing the CRC codingprocess, CRC data required for the error detection are generated.

The RS frame encoder 912 performs CRC coding on the RS coded enhanceddata in order to create the CRC code. The CRC code that is generated bythe CRC coding process may be used to indicate whether the enhanced datahave been damaged by an error while being transmitted through thechannel. The present invention may adopt other types of error detectioncoding methods, apart from the CRC coding method, and may also use theerror correction coding method so as to enhance the overall errorcorrection ability of the receiving system. For example, assuming thatthe size of one RS frame is 187*N bytes, that (235,187)-RS codingprocess is performed on each column within the RS frame, and that a CRCcoding process using a 2-byte (i.e., 16-bit) CRC checksum, then a RSframe having the size of 187*N bytes is expanded to a RS frame of235*(N+2) bytes. The RS frame expanded by the RS frame encoder 912 isinputted to the block processor 913. The block processor 913 codes theRS-coded and CRC-coded enhanced data at a coding rate of G/H. Then, theblock processor 913 outputs the G/H-rate coded enhanced data to thegroup formatter 914. In order to do so, the block processor 913identifies the block data bytes being inputted from the RS frame encoder912 as bits.

The block processor 913 may receive supplemental information data suchas signaling information, which include information on the system, andidentifies the supplemental information data bytes as data bits. Herein,the supplemental information data, such as the signaling information,may equally pass through the enhanced data randomizer 911 and the RSframe encoder 912 so as to be inputted to the block processor 913.Alternatively, the supplemental information data may be directlyinputted to the block processor 913 without passing through the enhanceddata randomizer 911 and the RS frame encoder 912. The signalinginformation corresponds to information required for receiving andprocessing data included in the data group in the receiving system. Suchsignaling information includes data group information, multiplexinginformation, and burst information.

As a G/H-rate encoder, the block processor 913 codes the inputted dataat a coding rate of G/H and then outputs the G/H-rate coded data. Forexample, if 1 bit of the input data is coded to 2 bits and outputted,then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).As an example of the present invention, it is assumed that the blockprocessor 913 performs a coding process at a coding rate of ½ (alsoreferred to as a ½-rate coding process) or a coding process at a codingrate of ¼ (also referred to as a ¼-rate coding process). Morespecifically, the block processor 913 codes the received enhanced dataand supplemental information data, such as the signaling information, ateither a coding rate of ½ or a coding rate of ¼. Thereafter, thesupplemental information data, such as the signaling information, areidentified and processed as enhanced data.

Since the ¼-rate coding process has a higher coding rate than the ½-ratecoding process, greater error correction ability may be provided.Therefore, in a later process, by allocating the ¼-rate coded data in anarea with deficient receiving performance within the group formatter914, and by allocating the ½-rate coded data in an area with excellentreceiving performance, the difference in the overall performance may bereduced. More specifically, in case of performing the ½-rate codingprocess, the block processor 913 receives 1 bit and codes the received 1bit to 2 bits (i.e., 1 symbol). Then, the block processor 913 outputsthe processed 2 bits (or 1 symbol). On the other hand, in case ofperforming the ¼-rate coding process, the block processor 913 receives 1bit and codes the received 1 bit to 4 bits (i.e., 2 symbols). Then, theblock processor 913 outputs the processed 4 bits (or 2 symbols).Additionally, the block processor 913 performs a block interleavingprocess in symbol units on the symbol-coded data. Subsequently, theblock processor 913 converts to bytes the data symbols that areblock-interleaved and have the order rearranged.

The group formatter 914 inserts the enhanced data outputted from theblock processor 913 (herein, the enhanced data may include supplementalinformation data such as signaling information including transmissioninformation) in a corresponding area within the data group, which isconfigured according to a pre-defined rule. Furthermore, in relationwith the data deinterleaving process, various types of places holders orknown data are also inserted in corresponding areas within the datagroup. At this point, the data group may be described by at least onehierarchical area. Herein, the data allocated to the each area may varydepending upon the characteristic of each hierarchical area.Additionally, each group is configured to include a fieldsynchronization signal.

The present invention shows an example of the data group being dividedinto three hierarchical areas: a head area, a body area, and a tailarea. Accordingly, in the data group that is inputted for the datadeinterleaving process, data are first inputted to the head area, theninputted to the body area, and inputted finally to the tail area. In theexample of the present invention, the head, body, and tail areas areconfigured so that the body area is not mixed with the main data areawithin the data group. Furthermore, in the present invention, the head,body, and tail areas may each be divided into lower hierarchical areas.For example, the head area may be divided into 3 lower hierarchicalareas: a far head (FH) area, a middle head (MH) area, and a near head(NH) area. The body area may be divided into 4 lower hierarchical areas:a first lower body (B1) area, a second lower body (B2) area, a thirdlower body (B3) area, and a fourth lower body (B4) area. And, finally,the tail area may be divided into 2 lower hierarchical areas: a far tail(FT) area and a near tail (NT) area.

In the example of the present invention, the group formatter 914 insertsthe enhanced data being outputted from the block processor 913 to themiddle head (MH) area, the near head (NH) area, the first to fourthlower body (B1 to B4) areas, and the near tail (NT) area. Herein, thetype of enhanced data may vary depending upon the characteristic of eacharea. The data group is divided into a plurality of areas so that eacharea may be used for different purposes. More specifically, areas havingless interference with the main data may show more enhanced receivingperformance as compared with area having more interference with the maindata. Additionally, when using the system in which the known data areinserted in the data group and then transmitted, and when a long set ofconsecutive known data is to be periodically (or regularly) inserted inthe enhanced data, the body area is capable of regularly receiving suchenhanced data having a predetermined length. However, since the enhanceddata may be mixed with the main data in the head and tail areas, it isdifficult to regularly insert the known data in these areas, and it isalso difficult to insert long known data sets that are consecutive inthese areas.

Details such as the size of the data group, the number of hierarchicalareas within the data group and the size of each hierarchical area, andthe number of enhanced data bytes that may be inserted in eachhierarchical area may vary depending upon the design of the systemdesigner. Therefore, the above-described embodiment is merely an examplethat can facilitate the description of the present invention. In thegroup formatter 914, the data group may be configured to include aposition (or place) in which the field synchronization signal is to beinserted. When assuming that the data group is divided into a pluralityof hierarchical areas as described above, the block processor 913 maycode the data that are to be inserted in each area at different codingrates.

In the present invention, based upon the areas that are each expected toshow different performance after the equalization process when using thechannel information that may be used for the channel equalizationprocess in the receiving system, a different coding rate may be appliedto each of these areas. For example, the block processor 913 codes theenhanced data that are to be inserted in the near head (NH) area and thefirst to fourth lower body (B1 to B4) areas at a ½-coding rate.Thereafter, the group formatter 914 may insert the ½-rate coded enhanceddata in the near head (NH) area and the first to fourth lower body (B1to B4) areas. On the other hand, the block processor 913 codes theenhanced data that are to be inserted in the middle head (MH) area andthe near tail (NT) area at a ¼-coding rate, which has greater errorcorrection ability than the ½-coding rate. Subsequently, the groupformatter 914 may insert the ½-rate coded enhanced data in the middlehead (MH) area and the near tail (NT) area. Furthermore, the blockprocessor 913 codes the enhanced data that are to be inserted in the farhead (FH) area and the far tail (FT) area at a coding rate having evengreater error correction ability than the ¼-coding rate. Thereafter, thegroup formatter 914 may inserts the coded enhanced data either in thefar head (FH) and far tail (FT) areas or in a reserved area for futureusage.

Apart from the enhanced data, the group formatter 913 may also insertsupplemental information data such as signaling information indicatingthe overall transmission information in the data group. Also, apart fromthe coded enhanced data outputted from the block processor 913, and inrelation with the data deinterleaving process in a later process, thegroup formatter 914 may also insert a MPEG header place holder, anon-systematic RS parity place holder, and a main data place holder inthe data group. Herein, the main data group place holder is insertedbecause the enhanced data and the main data may be mixed in the head andtail areas depending upon the input of the data deinterleaver. Forexample, based upon the output of the data after being deinterleaved,the place holder for the MPEG header may be allocated to the front ofeach data packet. Additionally, the group formatter 914 may eitherinsert known data generated according to a pre-defined rule, or insert aknown data place holder for inserting known data in a later process.Furthermore, a place holder for the initialization of the trellisencoder module 927 is inserted in a corresponding area. For example, theinitialization data place holder may be inserted at the beginning (orfront) of the data place sequence.

The output of the group formatter 914 is inputted to the datadeinterleaver 915. And, the data deinterleaver 915 performs an inverseprocess of the data interleaver deinterleaving the data and place holderwithin the data group being outputted from the group formatter 914.Thereafter, the data deinterleaver 915 outputs the deinterleaved data tothe packet formatter 916. Among the data deinterleaved and inputted, thepacket formatter 916 removes the main data place holder and RS parityplace holder that were allocated for the deinterleaving process from theinputted deinterleaved data. Thereafter, the remaining portion of thecorresponding data is grouped, and 4 bytes of MPEG header are insertedtherein. The 4-byte MPEG header is configured of a 1-byte MPEGsynchronization byte added to the 3-byte MPEG header place holder.

When the group formatter 914 inserts the known data place holder, thepacket formatter 916 may either insert actual known data in the knowndata place holder or output the known data place holder without anychange or modification for a replacement insertion in a later process.Afterwards, the packet formatter 916 divides the data within theabove-described packet-formatted data group into 188-byte unit enhanceddata packets (i.e., MPEG TS packets), which are then provided to thepacket multiplexer 921. The packet multiplexer 921 multiplexes the188-byte unit enhanced data packet and main data packet outputted fromthe packet formatter 916 according to a pre-defined multiplexing method.Subsequently, the multiplexed data packets are outputted to the datarandomizer 922. The multiplexing method may be modified or altered inaccordance with diverse variables of the system design.

As an example of the multiplexing method of the packet multiplexer 921,the enhanced data burst section and the main data section may beidentified along a time axis (or a chronological axis) and may bealternately repeated. At this point, the enhanced data burst section maytransmit at least one data group, and the main data section may transmitonly the main data. The enhanced data burst section may also transmitthe main data. If the enhanced data are outputted in a burst structure,as described above, the receiving system receiving only the enhanceddata may turn the power on only during the burst section so as toreceive the enhanced data, and may turn the power off during the maindata section in which main data are transmitted, so as to prevent themain data from being received, thereby reducing the power consumption ofthe receiving system.

When the data being inputted correspond to the main data packet, thedata randomizer 922 performs the same randomizing process of theconventional randomizer. More specifically, the MPEG synchronizationbyte included in the main data packet is discarded and a pseudo randombyte generated from the remaining 187 bytes is used so as to randomizethe data. Thereafter, the randomized data are outputted to the RSencoder/non-systematic RS encoder 923. However, when the inputted datacorrespond to the enhanced data packet, the MPEG synchronization byte ofthe 4-byte MPEG header included in the enhanced data packet isdiscarded, and data randomizing is performed only on the remaining3-byte MPEG header. Randomizing is not performed on the remainingportion of the enhanced data. Instead, the remaining portion of theenhanced data is outputted to the RS encoder/non-systematic RS encoder923. This is because the randomizing process has already been performedon the enhanced data by the enhanced data randomizer 911 in an earlierprocess. Herein, a data randomizing process may or may not be performedon the known data (or known data place holder) and the initializationdata place holder included in the enhanced data packet.

The RS encoder/non-systematic RS encoder 923 RS-codes the datarandomized by the data randomizer 922 or the data bypassing the datarandomizer 922. Then, the RS encoder/non-systematic RS encoder 923 addsa 20-byte RS parity to the coded data, thereby outputting theRS-parity-added data to the data interleaver 924. At this point, if theinputted data correspond to the main data packet, the RSencoder/non-systematic RS encoder 923 performs a systematic RS-codingprocess identical to that of the conventional receiving system on theinputted data, thereby adding the 20-byte RS parity at the end of the187-byte data. Alternatively, if the inputted data correspond to theenhanced data packet, the 20 bytes of RS parity gained by performing thenon-systematic RS-coding are respectively inserted in the decided paritybyte places within the enhanced data packet. Herein, the datainterleaver 924 corresponds to a byte unit convolutional interleaver.The output of the data interleaver 924 is inputted to the parity bytereplacer 925 and the non-systematic RS encoder 926.

Meanwhile, a memory within the trellis encoding module 927, which ispositioned after the parity byte replacer 925, should first beinitialized in order to allow the output data of the trellis encodingmodule 927 so as to become the known data defined based upon anagreement between the receiving system and the transmitting system. Morespecifically, the memory of the trellis encoding module 927 should firstbe initialized before the known data sequence being inputted istrellis-encoded. At this point, the beginning of the known data sequencethat is inputted corresponds to the initialization data place holderinserted by the group formatter 914 and not the actual known data.Therefore, a process of generating initialization data right before thetrellis-encoding of the known data sequence being inputted and a processof replacing the initialization data place holder of the correspondingtrellis encoding module memory with the newly generated initializationdata are required.

A value of the trellis memory initialization data is decided based uponthe memory status of the trellis encoding module 927, thereby generatingthe trellis memory initialization data accordingly. Due to the influenceof the replace initialization data, a process of recalculating the RSparity, thereby replacing the RS parity outputted from the trellisencoding module 927 with the newly calculated RS parity is required.Accordingly, the non-systematic RS encoder 926 receives the enhanceddata packet including the initialization data place holder that is to bereplaced with the initialization data from the data interleaver 924 andalso receives the initialization data from the trellis encoding module927. Thereafter, among the received enhanced data packet, theinitialization data place holder is replaced with the initializationdata. Subsequently, the RS parity data added to the enhanced data packetare removed. Then, a new non-systematic RS parity is calculated andoutputted to the parity byte replacer 925. Accordingly, the parity bytereplacer 925 selects the output of the data interleaver 924 as the datawithin the enhanced data packet, and selects the output of thenon-systematic RS encoder 926 as the RS parity. Thereafter, the paritybyte replacer 925 outputs the selected data.

Meanwhile, if the main data packet is inputted, or if the enhanced datapacket that does not include the initialization data place holder thatis to be replaced, the parity byte replacer 925 selects the data and RSparity outputted from the data interleaver 924 and directly outputs theselected data to the trellis encoding module 927 without modification.The trellis encoding module 927 converts the byte-unit data tosymbol-unit data and 12-way interleaves and trellis-encodes theconverted data, which are then outputted to the frame multiplexer 928.The frame multiplexer 928 inserts field synchronization and segmentsynchronization signals in the output of the trellis encoding module 927and then outputs the processed data to the transmitting unit 930.Herein, the transmitting unit 930 includes a pilot inserter 931, amodulator 932, and a radio frequency (RF) up-converter 933. Theoperation of the transmitting unit 930 is identical to the conventionaltransmitters. Therefore, a detailed description of the same will beomitted for simplicity.

FIG. 14 illustrates a block diagram of a demodulating unit included inthe receiving system according to another embodiment of the presentinvention. Herein, the demodulating unit may effectively process signalstransmitted from the transmitting system shown in FIG. 13. Referring toFIG. 14, the demodulating unit includes a demodulator 1001, a channelequalizer 1002, a known data detector 1003, a block decoder 1004, anenhanced data deformatter 1005, a RS frame decoder 1006, an enhanceddata derandomizer 1007, a data deinterleaver 1008, a RS decoder 1009,and a main data derandomizer 1010. For simplicity, the demodulator 1001,the channel equalizer 1002, the known data detector 1003, the blockdecoder 1004, the enhanced data deformatter 1005, the RS frame decoder1006, and the enhanced data derandomizer 1007 will be referred to as anenhanced data processor. And, the data deinterleaver 1008, the RSdecoder 1009, and the main data derandomizer 1010 will be referred to asa main data processor.

More specifically, the enhanced data including known data and the maindata are received through the tuner and inputted to the demodulator 1001and the known data detector 1003. The demodulator 1001 performsautomatic gain control, carrier wave recovery, and timing recovery onthe data that are being inputted, thereby creating baseband data, whichare then outputted to the equalizer 1002 and the known data detector1003. The equalizer 1002 compensates the distortion within the channelincluded in the demodulated data. Then, the equalizer 1002 outputs thecompensated data to the block decoder 1004.

At this point, the known data detector 1003 detects the known data placeinserted by the transmitting system to the input/output data of thedemodulator 1001 (i.e., data prior to demodulation or data afterdemodulation). Then, along with the position information, the known datadetector 1003 outputs the symbol sequence of the known data generatedfrom the corresponding position to the demodulator 1001 and theequalizer 1002. Additionally, the known data detector 1003 outputsinformation enabling the block decoder 1004 to identify the enhanceddata being additionally encoded by the transmitting system and the maindata that are not additionally encoded to the block decoder 1004.Furthermore, although the connection is not shown in FIG. 14, theinformation detected by the known data detector 1003 may be used in theoverall receiving system and may also be used in the enhanced dataformatter 1005 and the RS frame decoder 1006.

By using the known data symbol sequence when performing the timingrecovery or carrier wave recovery, the demodulating performance of thedemodulator 1001 may be enhanced. Similarly, by using the known data,the channel equalizing performance of the channel equalizer 1002 may beenhanced. Furthermore, by feeding-back the demodulation result of theblock demodulator 1004, the channel equalizing performance may also beenhanced. Herein, the channel equalizer 1002 may perform channelequalization through various methods. In the present invention, a methodof estimating a channel impulse response (CIR) for performing thechannel equalization process will be given as an example of the presentinvention. More specifically, in the present invention, the channelimpulse response (CIR) is differently estimated and applied inaccordance with each hierarchical area within the data group that aretransmitted from the transmitting system. Furthermore, by using theknown data having the position (or place) and contents pre-knownaccording to an agreement between the transmitting system and thereceiving system, so as to estimate the CIR, the channel equalizationprocess may be processed with more stability.

In the present invention, one data group that is inputted for channelequalization is divided into three hierarchical areas: a head area, abody area, and a tail area. Then, each of the areas is divided intolower hierarchical areas. More specifically, the head area may bedivided into a far head (FH) area, a middle head (MH) area, and a nearhead (NH) area. And, the tail area may be divided into a far tail (FT)area and a near tail (NT) area. Furthermore, based upon a long knowndata sequence, the body area may be divided into 4 lower hierarchicalareas: a first lower body (B1) area, a second lower body (B2) area, athird lower body (B3) area, and a fourth lower body (B4) area. Inperforming channel equalization on the data within the data group byusing the CIR estimated from the field synchronization signal and theknown data sequence, and in accordance with the characteristic of eacharea, either one of the estimated CIRs may be directly used withoutmodification, or a CIR created by interpolating or extrapolating aplurality of CIRs may be used.

Meanwhile, if the data being channel equalized and then inputted to theblock decoder 1004 correspond to the enhanced data on which additionalencoding and trellis encoding are both performed by the transmittingsystem, trellis-decoding and additional decoding processes are performedas inverse processes of the transmitting system. Alternatively, if thedata being channel equalized and then inputted to the block decoder 1004correspond to the main data on which additional encoding is notperformed and only trellis-encoding is performed by the transmittingsystem, only the trellis-decoding process is performed. The data groupdecoded by the block decoder 1004 is inputted to the enhanced datadeformatter 1005, and the main data packet is inputted to the datadeinterleaver 1008.

More specifically, if the inputted data correspond to the main data, theblock decoder 1004 performs Viterbi decoding on the inputted data, so asto either output a hard decision value or hard-decide a soft decisionvalue and output the hard-decided result. On the other hand, if theinputted correspond to the enhanced data, the block decoder 1004 outputseither a hard decision value or a soft decision value on the inputtedenhanced data. In other words, if the data inputted to the block decoder1004 correspond to the enhanced data, the block decoder 1004 performs adecoding process on the data encoded by the block processor and thetrellis encoder of the transmitting system. At this point, the output ofthe RS frame encoder included in the pre-processor of the transmittingsystem becomes an external code, and the output of the block processorand the trellis encoder becomes an internal code. In order to showmaximum performance of the external code when decoding such connectioncodes, the decoder of the internal code should output a soft decisionvalue. Therefore, the block decoder 1004 may output a hard decisionvalue on the enhanced data. However, when required, it is morepreferable that the block decoder 1004 outputs a soft decision value.

The present invention may also be used for configuring a reliability mapusing the soft decision value. The reliability map determines andindicates whether a byte corresponding to a group of 8 bits decided bythe code of the soft decision value is reliable. For example, when anabsolute value of the soft decision value exceeds a pre-determinedthreshold value, the value of the bit corresponding to the soft decisionvalue code is determined to be reliable. However, if the absolute valuedoes not exceed the pre-determined threshold value, then the value ofthe corresponding bit is determined to be not reliable. Further, if atleast one bit among the group of 8 bits, which are determined based uponthe soft decision value, is determined to be not reliable, then thereliability map indicates that the entire byte is not reliable. Herein,the process of determining the reliability by 1-bit units is merelyexemplary. The corresponding byte may also be indicated to be notreliable if a plurality of bits (e.g., 4 bits) is determined to be notreliable.

Conversely, when all of the bits are determined to be reliable withinone byte (i.e., when the absolute value of the soft value of all bitsexceeds the pre-determined threshold value), then the reliability mapdetermines and indicates that the corresponding data byte is reliable.Similarly, when more than 4 bits are determined to be reliable withinone data byte, then the reliability map determines and indicates thatthe corresponding data byte is reliable. The estimated numbers aremerely exemplary and do not limit the scope and spirit of the presentinvention. Herein, the reliability map may be used when performing errorcorrection decoding processes.

Meanwhile, the data deinterleaver 1008, the RS decoder 1009, and themain data derandomizer 1010 are blocks required for receiving the maindata. These blocks may not be required in a receiving system structurethat receives only the enhanced data. The data deinterleaver 1008performs an inverse process of the data interleaver of the transmittingsystem. More specifically, the data deinterleaver 1008 deinterleaves themain data being outputted from the block decode 1004 and outputs thedeinterleaved data to the RS decoder 1009. The RS decoder 1009 performssystematic RS decoding on the deinterleaved data and outputs thesystematically decoded data to the main data derandomizer 1010. The maindata derandomizer 1010 receives the data outputted from the RS decoder1009 so as to generate the same pseudo random byte as that of therandomizer in the transmitting system. The main data derandomizer 1010then performs a bitwise exclusive OR (XOR) operation on the generatedpseudo random data byte, thereby inserting the MPEG synchronizationbytes to the beginning of each packet so as to output the data in188-byte main data packet units.

Herein, the format of the data being outputted to the enhanced datadeformatter 1005 from the block decoder 1004 is a data group format. Atthis point, the enhanced data deformatter 1005 already knows thestructure of the input data. Therefore, the enhanced data deformatter1005 identifies the system information including signaling informationand the enhanced data from the data group. Thereafter, the identifiedsignaling information is transmitted to where the system information isrequired, and the enhanced data are outputted to the RS frame decoder1006. The enhanced data deformatter 1005 removes the known data, trellisinitialization data, and MPEG header that were included in the main dataand the data group and also removes the RS parity that was added by theRS encoder/non-systematic RS encoder of the transmitting system.Thereafter, the processed data are outputted to the RS frame decoder1006.

More specifically, the RS frame decoder 1006 receives the RS-coded andCRC-coded enhanced data from the enhanced data deformatter 1005 so as toconfigure the RS frame. The RS frame decoder 1006 performs an inverseprocess of the RS frame encoder included in the transmitting system,thereby correcting the errors within the RS frame. Then, the 1-byte MPEGsynchronization byte, which was removed during the RS frame codingprocess, is added to the error corrected enhanced data packet.Subsequently, the processed data are outputted to the enhanced dataderandomizer 1007. Herein, the enhanced data derandomizer 1007 performsa derandomizing process, which corresponds to an inverse process of theenhanced data randomizer included in the transmitting system, on thereceived enhanced data. Then, by outputting the processed data, theenhanced data transmitted from the transmitting system can be obtained.

According to an embodiment of the present invention, the RS framedecoder 1006 may also be configured as follows. The RS frame decoder1006 may perform a CRC syndrome check on the RS frame, thereby verifyingwhether or not an error has occurred in each row. Subsequently, the CRCchecksum is removed and the presence of an error is indicated on a CRCerror flag corresponding to each row. Then, a RS decoding process isperformed on the RS frame having the CRC checksum removed in a columndirection. At this point, depending upon the number of CRC error flags,a RS erasure decoding process may be performed. More specifically, bychecking the CRC error flags corresponding to each row within the RSframe, the number of CRC error flags may be determined whether it isgreater or smaller than the maximum number of errors, when RS decodingthe number of rows with errors (or erroneous rows) in the columndirection. Herein, the maximum number of errors corresponds to thenumber of parity bytes inserted during the RS decoding process. As anexample of the present invention, it is assumed that 48 parity bytes areadded to each column.

If the number of rows with CRC errors is equal to or smaller than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process is performedon the RS frame in the column direction. Thereafter, the 48 bytes ofparity data that were added at the end of each column are removed.However, if the number of rows with CRC errors is greater than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process.

As another embodiment of the present invention, the error correctionability may be enhanced by using the reliability map created whenconfiguring the RS frame from the soft decision value. Morespecifically, the RS frame decoder 1006 compares the absolute value ofthe soft decision value obtained from the block decoder 1004 to thepre-determined threshold value so as to determine the reliability of thebit values that are decided by the code of the corresponding softdecision value. Then, 8 bits are grouped to configure a byte. Then, thereliability information of the corresponding byte is indicated on thereliability map. Therefore, even if a specific row is determined to haveCRC errors as a result of the CRC syndrome checking process of thecorresponding row, it is not assumed that all of the data bytes includedin the corresponding row have error. Instead, only the data bytes thatare determined to be not reliable, after referring to the reliabilityinformation on the reliability map, are set to have errors. In otherwords, regardless of the presence of CRC errors in the correspondingrow, only the data bytes that are determined to be not reliable (orunreliable) by the reliability map are set as erasure points.

Thereafter, if the number of erasure points for each column is equal toor smaller than the maximum number of errors (e.g., 48), the RS erasuredecoding process is performed on the corresponding the column.Conversely, if the number of erasure points is greater than the maximumnumber of errors (e.g., 48), which may be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column. In other words, if the number of rows having CRCerrors is greater than the maximum number of errors (e.g., 48), whichmay be corrected by the RS erasure decoding process, either a RS erasuredecoding process or a general RS decoding process is performed on aparticular column in accordance with the number of erasure point withinthe corresponding column, wherein the number is decided based upon thereliability information on the reliability map. When the above-describedprocess is performed, the error correction decoding process is performedin the direction of all of the columns included in the RS frame.Thereafter, the 48 bytes of parity data added to the end of each columnare removed.

FIG. 15 illustrates a block diagram showing the structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Referring to FIG. 15, the digital broadcast receiving systemincludes a tuner 2001, a demodulating unit 2002, a demultiplexer 2003,an audio decoder 2004, a video decoder 2005, a native TV applicationmanager 2006, a channel manager 2007, a channel map 2008, a first memory2009, a data decoder 2010, a second memory 2011, a system manager 2012,a data broadcasting application manager 2013, a storage controller 2014,and a third memory 2015. Herein, the third memory 2015 is a mass storagedevice, such as a hard disk drive (HUD) or a memory chip. The tuner 2001tunes a frequency of a specific channel through any one of an antenna,cable, and satellite. Then, the tuner 2001 down-converts the tunedfrequency to an intermediate frequency (IF), which is then outputted tothe demodulating unit 2002. At this point, the tuner 2001 is controlledby the channel manager 2007. Additionally, the result and strength ofthe broadcast signal of the tuned channel are also reported to thechannel manager 2007. The data that are being received by the frequencyof the tuned specific channel include main data, enhanced data, andtable data for decoding the main data and enhanced data.

In the embodiment of the present invention, examples of the enhanceddata may include data provided for data service, such as Javaapplication data, HTML application data, XML data, and so on. The dataprovided for such data services may correspond either to a Java classfile for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the enhanced data may correspond to meta data.For example, the meta data use the XML application so as to betransmitted through a DSM-CC protocol.

The demodulating unit 2002 performs demodulation and channelequalization on the signal being outputted from the tuner 2001, therebyidentifying the main data and the enhanced data. Thereafter, theidentified main data and enhanced data are outputted in TS packet units.Examples of the demodulating unit 2002 is shown in FIG. 12 and FIG. 14.The demodulating unit shown in FIG. 12 and FIG. 14 is merely exemplaryand the scope of the present invention is not limited to the examplesset forth herein. In the embodiment given as an example of the presentinvention, only the enhanced data packet outputted from the demodulatingunit 2002 is inputted to the demultiplexer 2003. In this case, the maindata packet is inputted to another demultiplexer (not shown) thatprocesses main data packets. Herein, the storage controller 2014 is alsoconnected to the other demultiplexer in order to store the main dataafter processing the main data packets. The demultiplexer of the presentinvention may also be designed to process both enhanced data packets andmain data packets in a single demultiplexer.

The storage controller 2014 is interfaced with the demultiplexer so asto control instant recording, reserved (or pre-programmed) recording,time shift, and so on of the enhanced data and/or main data. Forexample, when one of instant recording, reserved (or pre-programmed)recording, and time shift is set and programmed in the receiving system(or receiver) shown in FIG. 15, the corresponding enhanced data and/ormain data that are inputted to the demultiplexer are stored in the thirdmemory 2015 in accordance with the control of the storage controller2014. The third memory 2015 may be described as a temporary storage areaand/or a permanent storage area. Herein, the temporary storage area isused for the time shifting function, and the permanent storage area isused for a permanent storage of data according to the user's choice (ordecision).

When the data stored in the third memory 2015 need to be reproduced (orplayed), the storage controller 2014 reads the corresponding data storedin the third memory 2015 and outputs the read data to the correspondingdemultiplexer (e.g., the enhanced data are outputted to thedemultiplexer 2003 shown in FIG. 15). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 2015 is limited, the compression encoded enhanced dataand/or main data that are being inputted are directly stored in thethird memory 2015 without any modification for the efficiency of thestorage capacity. In this case, depending upon the reproduction (orreading) command, the data read from the third memory 2015 pass troughthe demultiplexer so as to be inputted to the corresponding decoder,thereby being restored to the initial state.

The storage controller 2014 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 2015 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 2014compression encodes the inputted data and stored the compression-encodeddata to the third memory 2015. In order to do so, the storage controller2014 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 2014.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 2015, the storage controller2014 scrambles the input data and stores the scrambled data in the thirdmemory 2015. Accordingly, the storage controller 2014 may include ascramble algorithm for scrambling the data stored in the third memory2015 and a descramble algorithm for descrambling the data read from thethird memory 2015. Herein, the definition of scramble includesencryption, and the definition of descramble includes decryption. Thescramble method may include using an arbitrary key (e.g., control word)to modify a desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 2003 receives the real-time data outputtedfrom the demodulating unit 2002 or the data read from the third memory2015 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 2003 performs demultiplexing on theenhanced data packet. Therefore, in the present invention, the receivingand processing of the enhanced data will be described in detail. Itshould also be noted that a detailed description of the processing ofthe main data will be omitted for simplicity starting from thedescription of the demultiplexer 2003 and the subsequent elements.

The demultiplexer 2003 demultiplexes enhanced data and program specificinformation/program and system information protocol (PSI/PSIP) tablesfrom the enhanced data packet inputted in accordance with the control ofthe data decoder 2010. Thereafter, the demultiplexed enhanced data andPSI/PSIP tables are outputted to the data decoder 2010 in a sectionformat. In order to extract the enhanced data from the channel throughwhich enhanced data are transmitted and to decode the extracted enhanceddata, system information is required. Such system information may alsobe referred to as service information. The system information mayinclude channel information, event information, etc. In the embodimentof the present invention, the PSI/PSIP tables are applied as the systeminformation. However, the present invention is not limited to theexample set forth herein. More specifically, regardless of the name, anyprotocol transmitting system information in a table format may beapplied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number. The STTtransmits information on the current data and timing information. TheRRT transmits information on region and consultation organs for programratings. The ETT transmits additional description of a specific channeland broadcast program. The EIT transmits information on virtual channelevents (e.g., program title, program start time, etc.). The DCCT/DCCSCTtransmits information associated with automatic (or direct) channelchange. And, the MGT transmits the versions and PID information of theabove-mentioned tables included in the PSIP.

Each of the above-described tables included in the PSI/PSIP isconfigured of a basic unit referred to as a “section”, and a combinationof one or more sections forms a table. For example, the VCT may bedivided into 256 sections. Herein, one section may include a pluralityof virtual channel information. However, a single set of virtual channelinformation is not divided into two or more sections. At this point, thereceiving system may parse and decode the data for the data service thatare transmitting by using only the tables included in the PSI, or onlythe tables included in the PISP, or a combination of tables included inboth the PSI and the PSIP. In order to parse and decode the data for thedata service, at least one of the PAT and PMT included in the PSI, andthe VCT included in the PSIP is required. For example, the PAT mayinclude the system information for transmitting the data correspondingto the data service, and the PID of the PMT corresponding to the dataservice data (or program number). The PMT may include the PID of the TSpacket used for transmitting the data service data. The VCT may includeinformation on the virtual channel for transmitting the data servicedata, and the PID of the TS packet for transmitting the data servicedata.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up. The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective Si tables (i.e., a bouquet associate table(BAT), a running status table (RST) and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRE to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, the enhanced data included in the payloadwithin the TS packet consist of a digital storage media-command andcontrol (DSM-CC) section format. However, the TS packet including thedata service data may correspond either to a packetized elementarystream (PES) type or to a section type. More specifically, either thePES type data service data configure the TS packet, or the section typedata service data configure the TS packet. The TS packet configured ofthe section type data will be given as the example of the presentinvention. At this point, the data service data are includes in thedigital storage media-command and control (DSM-CC) section. Herein, theDSM-CC section is then configured of a 188-byte unit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge that data broadcastingincluding enhanced data (i.e., the enhanced data) is being received. Atthis point, the enhanced data may be transmitted by a data carouselmethod. The data carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the data decoder 2010, thedemultiplexer 2003 performs section filtering, thereby discardingrepetitive sections and outputting only the non-repetitive sections tothe data decoder 2010. The demultiplexer 2003 may also output only thesections configuring desired tables (e.g., VCT) to the data decoder 2010by section filtering. Herein, the VCT may include a specific descriptorfor the enhanced data. However, the present invention does not excludethe possibilities of the enhanced data being included in other tables,such as the PMT. The section filtering method may include a method ofverifying the PID of a table defined by the MGT, such as the VCT, priorto performing the section filtering process. Alternatively, the sectionfiltering method may also include a method of directly performing thesection filtering process without verifying the MGT, when the VCTincludes a fixed PID (i.e., a base PID). At this point, thedemultiplexer 2003 performs the section filtering process by referringto a table_id field, a version_number field, a section_number field,etc.

As described above, the method of defining the PID of the VCT broadlyincludes two different methods. Herein, the PID of the VCT is a packetidentifier required for identifying the VCT from other tables. The firstmethod consists of setting the PID of the VCT so that it is dependent tothe MGT. In this case, the receiving system cannot directly verify theVCT among the many PSI and/or PSIP tables. Instead, the receiving systemmust check the PID defined in the MGT in order to read the VCT. Herein,the MGT defines the PID, size, version number, and so on, of diversetables. The second method consists of setting the PID of the VCT so thatthe PID is given a base PID value (or a fixed PID value), thereby beingindependent from the MGT. In this case, unlike in the first method, theVCT according to the present invention may be identified without havingto verify every single PID included in the MGT. Evidently, an agreementon the base PID must be previously made between the transmitting systemand the receiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer2003 may output only an application information table (AIT) to the datadecoder 2010 by section filtering. The AIT includes information on anapplication being operated in the receiving system for the data service.The AIT may also be referred to as an XAIT, and an AMT. Therefore, anytable including application information may correspond to the followingdescription. When the AIT is transmitted, a value of ‘0x05’ may beassigned to a stream_type field of the PMT. The AIT may includeapplication information, such as application name, application version,application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_network_id field, the transport_stream_id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 2011 by the data decoder 2010.

The data decoder 2010 parses the DSM-CC section configuring thedemultiplexed enhanced data. Then, the enhanced data corresponding tothe parsed result are stored as a database in the second memory 2011.The data decoder 2010 groups a plurality of sections having the sametable identification (table_id) so as to configure a table, which isthen parsed. Thereafter, the parsed result is stored as a database inthe second memory 2011. At this point, by parsing data and/or sections,the data decoder 2010 reads all of the remaining actual section datathat are not section-filtered by the demultiplexer 2003. Then, the datadecoder 2010 stores the read data to the second memory 2011. The secondmemory 2011 corresponds to a table and data carousel database storingsystem information parsed from tables and enhanced data parsed from theDSM-CC section. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT.

When the VCT is parsed, information on the virtual channel to whichenhanced data are transmitted may be obtained. The obtained applicationidentification information, service component identificationinformation, and service information corresponding to the data servicemay either be stored in the second memory 2011 or be outputted to thedata broadcasting application manager 2013. In addition, reference maybe made to the application identification information, service componentidentification information, and service information in order to decodethe data service data. Alternatively, such information may also preparethe operation of the application program for the data service.Furthermore, the data decoder 2010 controls the demultiplexing of thesystem information table, which corresponds to the information tableassociated with the channel and events. Thereafter, an A.V PID list maybe transmitted to the channel manager 2007.

The channel manager 2007 may refer to the channel map 2008 in order totransmit a request for receiving system-related information data to thedata decoder 2010, thereby receiving the corresponding result. Inaddition, the channel manager 2007 may also control the channel tuningof the tuner 2001. Furthermore, the channel manager 2007 may directlycontrol the demultiplexer 2003, so as to set up the A/V PID, therebycontrolling the audio decoder 2004 and the video decoder 2005. The audiodecoder 2004 and the video decoder 2005 may respectively decode andoutput the audio data and video data demultiplexed from the main datapacket. Alternatively, the audio decoder 2004 and the video decoder 2005may respectively decode and output the audio data and video datademultiplexed from the enhanced data packet. Meanwhile, when theenhanced data include data service data, and also audio data and videodata, it is apparent that the audio data and video data demultiplexed bythe demultiplexer 2003 are respectively decoded by the audio decoder2004 and the video decoder 2005. For example, an audio-coding (AC)-3decoding algorithm may be applied to the audio decoder 2004, and aMPEG-2 decoding algorithm may be applied to the video decoder 2005.

Meanwhile, the native TV application manager 2006 operates a nativeapplication program stored in the first memory 2009, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 2006 displays the user request on a screenthrough a graphic user interface (GUT), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 2006 and the databroadcasting application manager 2013. Furthermore, the native TVapplication manager 2006 controls the channel manager 2007, therebycontrolling channel-associated, such as the management of the channelmap 2008, and controlling the data decoder 2010. The native TVapplication manager 2006 also controls the GUI of the overall receivingsystem, thereby storing the user request and status of the receivingsystem in the first memory 2009 and restoring the stored information.

The channel manager 2007 controls the tuner 2001 and the data decoder2010, so as to managing the channel map 2008 so that it can respond tothe channel request made by the user. More specifically, channel manager2007 sends a request to the data decoder 2010 so that the tablesassociated with the channels that are to be tuned are parsed. Theresults of the parsed tables are reported to the channel manager 2007 bythe data decoder 2010. Thereafter, based on the parsed results, thechannel manager 2007 updates the channel map 2008 and sets up a PID inthe demultiplexer 2003 for demultiplexing the tables associated with thedata service data from the enhanced data.

The system manager 2012 controls the booting of the receiving system byturning the power on or off. Then, the system manager 2012 stores ROMimages (including downloaded software images) in the first memory 2009.More specifically, the first memory 2009 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 2011 so as to provide the user with the dataservice. If the data service data are stored in the second memory 2011,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 2009 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stored managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory2009 upon the shipping of the receiving system, or be stored in thefirst 2009 after being downloaded. The application program for the dataservice (i.e., the data service providing application program) stored inthe first memory 2009 may also be deleted, updated, and corrected.Furthermore, the data service providing application program may bedownloaded and executed along with the data service data each time thedata service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 2013 operates thecorresponding application program stored in the first memory 2009 so asto process the requested data, thereby providing the user with therequested data service. And, in order to provide such data service, thedata broadcasting application manager 2013 supports the graphic userinterface (GUI). Herein, the data service may be provided in the form oftext (or short message service (SMS)), voice message, still image, andmoving image. The data broadcasting application manager 2013 may beprovided with a platform for executing the application program stored inthe first memory 2009. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 2013 executing the data serviceproviding application program stored in the first memory 2009, so as toprocess the data service data stored in the second memory 2011, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiving system that is not equipped with anelectronic map and/or a GPS system in the form of at least one of a text(or short message service (SMS)), a voice message, a graphic message, astill image, and a moving image. In this case, is a GPS module ismounted on the receiving system shown in FIG. 15, the GPS modulereceives satellite signals transmitted from a plurality of low earthorbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager2013.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 2011, the first memory 2009, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 2013, the dataservice data stored in the second memory 2011 are read and inputted tothe data broadcasting application manager 2013. The data broadcastingapplication manager 2013 translates (or deciphers) the data service dataread from the second memory 2011, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal.

FIG. 16 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 16, the digitalbroadcast receiving system includes a tuner 3001, a demodulating unit3002, a demultiplexer 3003, a first descrambler 3004, an audio decoder3005, a video decoder 3006, a second descrambler 3007, an authenticationunit 3008, a native TV application manager 3009, a channel manager 3010,a channel map 3011, a first memory 3012, a data decoder 3013, a secondmemory 3014, a system manager 3015, a data broadcasting applicationmanager 3016, a storage controller 3017, a third memory 3018, and atelecommunication module 3019. Herein, the third memory 3018 is a massstorage device, such as a hard disk drive (HDD) or a memory chip. Also,during the description of the digital broadcast (or television or DTV)receiving system shown in FIG. 16, the components that are identical tothose of the digital broadcast receiving system of FIG. 15 will beomitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descrample the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an authentication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 3004 and 3007, and the authentication means will bereferred to as an authentication unit 3008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.16 illustrates an example of the descramblers 3004 and 3007 and theauthentication unit 3008 being provided inside the receiving system,each of the descramblers 3004 and 3007 and the authentication unit 3008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 3008, the scrambled broadcastingcontents are descrambled by the descramblers 3004 and 3007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 3008 and thedescramblers 3004 and 3007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 3001 and the demodulating unit 3002. Then, the system manager3015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 3002 may be included as ademodulating means according to embodiments of the present invention asdescribed in FIG. 12 and FIG. 14. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 3015 decides that the received broadcasting contentshave been scrambled, then the system manager 3015 controls the system tooperate the authentication unit 3008. As described above, theauthentication unit 3008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 3008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 3008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advances with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 3008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 3008 determines that the two types ofinformation conform to one another, then the authentication unit 3008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or antherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem-specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 3008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 3008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 3008 determines that the information conform to eachother, then the authentication unit 3008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 3008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the above-mentioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 3015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 3015 transmits thepayment information to the remote transmitting system through thetelecommunication module 3019.

The authentication unit 3008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 3008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 3008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 3008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 3004 and 3007. Herein,the first and second descramblers 3004 and 3007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 3004 and 3007, so as to perform the descrambling process.More specifically, the first and second descramblers 3004 and 3007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 3004 and 3007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 3004 and 3007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 3004 and 3007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 3015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 3012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 3008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 3008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 3015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 3012 upon the shipping of the presentinvention, or be downloaded to the first memory 3012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 3016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 3003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 3004 and 3007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 3004 and3007. Each of the descramblers 3004 and 3007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 3004 and 3007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 3018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced). Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 3017, the storage controller 3017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 3018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associated with theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 3019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 3019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information). Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 3019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module3019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1×EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile internet,WiBro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 3019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 3003 receives either the real-time data outputted from thedemodulating unit 3002 or the data read from the third memory 3018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 3003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 3004 receives the demultiplexed signals from thedemultiplexer 3003 and then descrambles the received signals. At thispoint, the first descrambler 3004 may receive the authentication resultreceived from the authentication unit 3008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 3005 and the video decoder 3006 receive the signalsdescrambled by the first descrambler 3004, which are then decoded andoutputted. Alternatively, if the first descrambler 3004 did not performthe descrambling process, then the audio decoder 3005 and the videodecoder 3006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 3007 and processed accordingly.

As described above, the DTV transmitting system and receiving system andmethod of processing data according to the present invention haveadvantages in that errors rarely occur when enhanced data is transmittedthrough channels and they also are compatible with the conventionalreceivers. Also, the present invention can receive enhanced data withouterrors through channels in which ghost images and noise are a seriousproblem, compared with the conventional receiver.

Also, in order to group a plurality of enhanced data packets havinginformation, multiplex the group with main data, and transmit them, thepresent invention stratifies the group to form a plurality of regions,and classifies types of inserted data, and processing methods, etc.,according to characteristics of stratified regions. Therefore, receivingperformance of a receiving system can be enhanced. Especially, aspre-processes are performed differently according to types of datainserted to the stratified regions in the group and types of inputtedenhanced data, receiving performance of a receiving system can befurther enhanced. Also, as soft decision decoding for the enhanced datais performed in the receiving end, decoding performance of the receivingsystem can be increased.

In addition, the present invention is more effective when it is appliedto portable and mobile receivers whose channels vary significantly.Also, the present invention clearly shows its effect in receivers whichrequire resistance to noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of processing main and enhanced data in a DTV transmitting system, the method comprising: pre-processing first enhanced data having a high priority by coding the first enhanced data for forward error correction (FEC) at a first coding rate and expanding the FEC-coded first enhanced data at a first expansion rate; pre-processing second enhanced data having a low priority by coding the second enhanced data for forward error correction (FEC) at a second coding rate and expanding the FEC-coded second enhanced data at a second expansion rate; generating enhanced data packets including the pre-processed first and second enhanced data; multiplexing the enhanced data packets with main data packets including the main data; RS-coding the multiplexed data packets in a first RS encoder by adding first systematic parity data to each main data packet and adding non-systematic RS parity holders to each enhanced data packet; interleaving the RS-coded data packets in a first data interleaver; and processing the interleaved data packets in a block processor by coding each block of enhanced data in the interleaved enhanced data packets and bypassing the interleaved main data packets.
 2. The method of claim 1, wherein a known data sequence is periodically included in the interleaved enhanced data packets.
 3. The method of claim 1, wherein the first coding rate is different from the second coding rate.
 4. The method of claim 1, wherein the first coding rate is higher than the second coding rate.
 5. The method of claim 1, wherein the first coding rate is lower than the second coding rate.
 6. The method of claim 1, wherein the first expansion rate is different from the second expansion rate.
 7. The method of claim 1, wherein the first data interleaver outputs a group of interleaved data packets including a head, a body, and a tail.
 8. The method of claim 7, wherein the body includes a plurality of consecutive enhanced data packets only.
 9. The method of claim 8, wherein a known data sequence is periodically included in the plurality of consecutive enhanced data packets.
 10. The method of claim 8, wherein the plurality of consecutive enhanced data packets are high-priority enhanced data packets.
 11. The method of claim 8, wherein low-priority enhanced data packets are included in at least one of the head and tail.
 12. The method of claim 1, wherein processing the interleaved data packets in a block processor comprises: demultiplexing the interleaved main and enhanced data packets; encoding each block of enhanced data in the demultiplexed enhanced data packets; temporarily storing the demultiplexed main data packets in a buffer; and multiplexing the encoded block enhanced data with the main data stored in the buffer.
 13. The method of claim 1, further comprising: de-interleaving the main and enhanced data packets processed in the block processor; removing the first systematic parity data and the non-systematic RS parity place holders from the de-interleaved main and enhanced data packets, respectively.
 14. The method of claim 13, further comprising: RS-coding the parity-removed main and enhanced data packets in a second RS coder by adding second systematic parity data to each main data packet and adding non-systematic parity data to each enhanced data packet; and interleaving the main and enhanced data packets outputted from the second RS coder in a second data interleaver.
 15. The method of claim 14, further comprising: converting the data packets outputted from the second data interleaver into symbols; and trellis-encoding the converted symbols.
 16. A DTV transmitting system for processing main and enhanced data, the DTV transmitting system comprising: a first pre-processor for pre-processing first enhanced data having a high priority by coding the first enhanced data for forward error correction (FEC) at a first coding rate and expanding the FEC-coded first enhanced data at a first expansion rate; a second pre-processor for pre-processing second enhanced data having a low priority by coding the second enhanced data for forward error correction (FEC) at a second coding rate and expanding the FEC-coded second enhanced data at a second expansion rate; a data formatter for generating enhanced data packets including the pre-processed first and second enhanced data; a first multiplexer for multiplexing the enhanced data packets with main data packets including the main data; a first RS encoder for RS-coding the multiplexed data packets, the RS encoder adding first systematic parity data to each main data packet and adding non-systematic RS parity place holders to each enhanced data packet; a first data interleaver for interleaving the RS-coded data packets; and a block processor for coding each block of enhanced data in the interleaved enhanced data packets and bypassing the interleaved main data packets.
 17. The DTV transmitting system of claim 16, wherein a known data sequence is periodically included in the interleaved enhanced data packets.
 18. The DTV transmitting system of claim 16, wherein the first coding rate is different from the second coding rate.
 19. The DTV transmitting system of claim 16, wherein the first coding rate is higher than the second coding rate.
 20. The DTV transmitting system of claim 16, wherein the first coding rate is lower than the second coding rate.
 21. The DTV transmitting system of claim 16, wherein the first expansion rate is different from the second expansion rate.
 22. The DTV transmitting system of claim 16, wherein the first data interleaver outputs a group of interleaved data packets having a head, a body, and a tail.
 23. The DTV transmitting system of claim 22, wherein the body includes a plurality of consecutive enhanced data packets only.
 24. The DTV transmitting system of claim 23, wherein a known data sequence is periodically included in the plurality of consecutive enhanced data packets.
 25. The DTV transmitting system of claim 23, wherein the plurality of consecutive enhanced data packets are high-priority enhanced data packets.
 26. The DTV transmitting system of claim 23, wherein low-priority enhanced data packets are included in at least one of the head and tail.
 27. The DTV transmitting system of claim 16, wherein the block processor comprises: a demultiplexer for demultiplexing the interleaved main and enhanced data packets; a block encoder for encoding each block of enhanced data in the demultiplexed enhanced data packets; a buffer for temporarily storing the demultiplexed main data; and a second multiplexer for multiplexing the encoded block of enhanced data with the main data stored in the buffer.
 28. The DTV transmitting system of claim 16, further comprising: a data de-interleaver for de-interleaving the main and enhanced data packets outputted from the block processor; and an RS parity remover for removing the first systematic parity data and the non-systematic RS parity place holders from the de-interleaved main and enhanced data packets, respectively.
 29. The DTV transmitting system of claim 28, further comprising: a second RS encoder for RS-coding the main and enhanced data packets outputted from the RS parity remover, the second RS encoder adding second systematic parity data to each main data packet and adding non-systematic parity data to each enhanced data packet; and a second data interleaver for interleaving the main and enhanced data packets outputted from the second RS encoder.
 30. The DTV transmitting system of claim 29, further comprising: a byte-symbol converter for converting the data packets outputted from the second data interleaver into symbols; and a trellis encoder for trellis-encoding the converted symbols. 